If you use integration like Github, or API, or CLI for the file upload, you can specify the language availability option. I think it’s not presented in UI just not to confuse users.
For the file, Word’s .docx files are not key-based, Crowdin can’t match old strings with their translations if you update the file, that is why all translation that goes after the updated string is deleted because the system thinks that these are new strings.
Run the pre-translation from TM, it will bring the suggestions back 