The female lead reveals real feelings in Russian, unaware her classmate understands — a consistent comedic engine.
The central dramatic irony extends across the ongoing series rather than being a one-episode gag.
Yes — this is revealed early and is the core dramatic irony the show's comedy runs on, since Alya assumes he can't understand her Russian-language asides.
Check current status for the latest — the core romantic gimmick is designed to sustain across an ongoing series rather than resolve quickly.