If I set field translate:false and then save default language page it stores all the data just fine. But when I save the alternate language page it will also store untranslatable values to selected language. This makes it impossible to change the value from alternate language. E.g. if I edit default language, the alternate language will still use previous values, and not the values from changed default language.
That’s definitely not how it should be. I’ll create an issue on GitHub.
Edit: Done: https://github.com/getkirby/panel/issues/781
A fix for this will be included in the next Kirby release.