You can, probably, create an AppleScript that will detect the language of the email one way or another.
The script will need to run the email through Google Translate, ChatGPT, or numerous other similar services.
It's probably not a trivial task, though (depending on scripting experience). It might be, potentially, easier in Sequoia with the built-in Apple Intelligence - but that's just my speculation.
Also, you may lose legitimate emails if you ever start receiving legitimate communication from non-English speaking bodies and forget to disable this filter.