frontend-item-form with json.parse errors

1 can you test with english language
2 can you do a test with cassopedia
regards

EN / myTemplate
Uncaught SyntaxError: JSON.parse: bad escaped character at line 1 column 870 of the JSON data

DE / myTemplate
Uncaught SyntaxError: JSON.parse: bad escaped character at line 1 column 957 of the JSON data

EN / cassiopeia
Uncaught SyntaxError: JSON.parse: bad escaped character at line 1 column 870 of the JSON dat

DE / cassiopeia
Uncaught SyntaxError: JSON.parse: bad escaped character at line 1 column 957 of the JSON data

can you test with beta version : github.com/FLEXIcontent/flexicontent-cck...efs/heads/master.zip ?

nope, still I get:

Uncaught SyntaxError: JSON.parse: bad escaped character at line 1 column 957 of the JSON data
loadOptions http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
loadOptions http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
getOptions http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
<anonymous> http://localhost/[...]/media/system/js/keepalive.min.js?94b7329e7ead5aa8faa224be8070af5c97f08af6:1
core.min.js:1:2364
Uncaught SyntaxError: JSON.parse: bad escaped character at line 1 column 957 of the JSON data
loadOptions http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
loadOptions http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
getOptions http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
<anonymous> http://localhost/[...]/media/system/js/messages.min.js?7425e8d1cb9e4f061d5e30271d6d99b085344117:1
EventListener.handleEvent* http://localhost/[...]/media/system/js/messages.min.js?7425e8d1cb9e4f061d5e30271d6d99b085344117:1
core.min.js:1:2364
Uncaught SyntaxError: JSON.parse: bad escaped character at line 1 column 957 of the JSON data
loadOptions http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
loadOptions http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
getOptions http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
_ http://localhost/[...]/media/system/js/core.min.js?9c761ae035a6bd778a710e6c0f5ff7de049b67a3:1
handle_PostInit http://localhost/[...]/components/com_flexicontent/assets/js/plupload-extend.js?7adba8519894cf32bcf4644bf7f7cde3:430
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:29
trigger http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
init http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:29
p http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:29
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
onready http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:29
handleEventProps http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
d http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
init http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
d http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
trigger http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
o http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
setTimeout handler*connectRuntime/o/< http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
d http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
trigger http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
init http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:14
o http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
connectRuntime http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
init http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:14
p http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:29
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
onready http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:29
handleEventProps http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
setTimeout handler*dispatchEvent/</< http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
setTimeout handler*dispatchEvent/</< http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
d http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
trigger http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
init http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:14
exec http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
shimExec http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
exec http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
init http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
d http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
trigger http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
o http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
setTimeout handler*connectRuntime/o/< http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
n http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
d http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
dispatchEvent http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
trigger http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
init http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:14
o http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
connectRuntime http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:13
init http://localhost/[...]/components/com_flexicontent/librairies/plupload/js/plupload.full.min.js:1

[setup]
j 4.4.0
fc see your link

[languages X templates]
I tried
- myTmpl in german
- myTmpl in english
- Cassiopeia in german
- Cassiopeia in english

i tried with and without activated i18n-relevant plugins (lang-switcher etc.)

PS: did you get my DM with link to test online?
PPS: sorry for being slow, many projects parallel

hello i tested and yes you have a problem but i can't reproduce in my other sites ...
could you send me an admin access ?