It's not just how well the language is represented. Obscure-ish APIs can trip up LLMs. I've been using Antigravity for a Flutter project that uses ATProto. Gemini is very strong at Dart coding, which makes picking up my 17th managed language a breeze. It's also very good at Flutter UI elements. It was noticeably less good at ATProto and its Dart API.

The characteristics of failures have been interesting: As I anticipated it might be, an over ambitious refactoring was a train wreck, easily reverted. But something as simple as regenerating Android launcher icons in a Flutter project was a total blind spot. I had to Google that like some kind of naked savage running through the jungle.

I have a vibe coded fantasy console. Getting Doom running on it was easy.

Getting the Doom sound working on it involved me setting there typing "No I can't hear anything" over and over until it magically worked...

Maybe I should have written a helper program to listen using the microphone or something.