You could create a filter, if you can find a search that will hit only the emails you want, and have all matching messages deleted? Or at least "never send to spam" but instead moved to a special folder if you want to review them too.
I thought that maybe some characters that never show up in your language like ф peraps? But apparently Gmail doesn't search like that, here's a good overview from another answer:
The Gmail search functionality works based on what I would describe as tokens. A token is any sequence of alphanumeric characters separated by a space or by other non-alphanumeric characters such as underscore, full stop (period), "@", dash, etc.. So in firstname.lastname@example.org there are 4 tokens: "peter", "ford23", "example" and "com".
Wildcards within tokens do not work.
So Gmail only searches by words or parts of emails. Even the
. in the examples below may be unnecessary (
from:.ru may be the same as
Or something like
from:.ru should match all messages whose from address contains .ru (I tested
from:(.com) that matches anything.com addresses, while
from:(.co) matches emails containing .co like
There may be a combination of "tokens"/words in the
body: that might match enough messages...
There used to be a good language search, but apparently it doesn't work anymore. This guy said that Gmail could search emails by language using
lang:ru for Russian. More language codes should be here. I don't think I have any emails like that so couldn't test, but trying
lang:en didn't show any hits, so it looks like it's no longer available.
Or, you could try a filter for the "false positive" spam you frequently see and keep those out of the spam folder, maybe search for your name or something unique? That would probably result in a lot of spam not in the spam folder though.