[Closed] Multiple issues with Advanced Translation Editor

Background of the issue:
I am trying to translate my content with the advanced translation editor. The issue can be seen at the following link: hidden link

Symptoms:
I am experiencing several issues:
- a percentage that often does not reach 100% even after re-validating with Alt+Enter (cf recording : the translation is stuck à 98%)
- if I reload the "score reaches 100%"... But then the translated page can't be displayed (cf end of recording - 404 page). Only moving to WordPress editor + validation seems to solve the issue.
- some translations disappear (not visible on the recording)
- missing translations (2nd part of the list - cf recording)
- the editor sometimes hangs and I can't select any fields for a while, and some content isn't available for translation. (not visible n the recording)

Recording: hidden link

Questions:
Are these known issues? Any workarounds?