9/10 here. The one I didn't get is one where either a coma or a semi-colon is fine.
Raised as trilingual here - English is only my third language after French (albeit the Belgian version thereof), and Polish. I also have a good working knowledge of German, Dutch (Flemish), and a smattering of Russian.
I've also written both academically (research papers, PhD thesis) and professionally (motorsport journalist and researcher / historian). As a cat show judge, I also have to produce a written report for every exhibit I handle. One of my previous editors said that he never had to proof read any of the articles or race reports I submitted for publication because they were spot on and ready to drop into his desktop publishing software.
My proofreading friend, despite being a proficient linguist (having written GCSE text books for German, and speaks German and Italian fluently, and French as well but not as well as he'd like) will only proofread
into English, as he says you can always tell when someone is blagging being a native speaker... often the random prepositions will trip them up, or the auxiliary/modal verbs. But he wasn't raised multi-lingual.
By the sound of it, being raised trilingual, you'd be happy to proofread in any of the three languages, as you probably just know what *sounds* right, even before you analyse the vocab or grammar, or use of idioms.