Option "Ignore system input language" should be default

This is your problem, screencasted.

LatinUsingEnglish

I have a document with Latin. I put cursor there, and type a Latin phrase. But it becomes English (and gets spell-checked as such, and gets a mark), because I use English system input language.

Exactly, it should NOT become English. Why?? Because it’s NOT English.
This does not happen with other text editors. This is problematic.
You can set the language to Latin, but Writer will set again every new paragraph to English without respecting your choice.
Unless the option “Ignore System Input Language” is checked.
In my opinion:

  1. If Writer has not enough AI to understand the language, it should just trust the user.
    By default
  2. the option of “Ignoring System input language” should be in the menu that appears when you click the language name, on the bottom of your document. At least people won’t need to have to search in Google to find this hidden option that has the power of disabling that evil problem.

And what if your language is not in an official language recognized by Windows? For Example a dialect or Esperanto… no solution because it’s impossible to set a language not recognized by Windows. Your document will be changed without any reason to the input language.
But if the option “Ignoring System input language” is checked (and it should be by default), problems disappear

Not what I see, if I use paragraph styles. For my few bi-lingual files I have two variants of textbody like tb-en and tb-de and if I set the same style as “next style” my language never changes.
.
For a “translation” with alternating language I can set tb-en as successor of tb-de and vice-versa and language will switch automatic. No special settings necessary on Win10 pro.

What about saving a working copy of your profile and using this backup also on the new setup. Then your valuable setting should be kept.

Yes, it could help but saving, maintaining, copying and moving a configuration is anyway an additional work.
But it would help only me. I would like that behaviour to be solved in general, not only for me.