I'm professional c# dev but not in game dev.
Nowadays, C# is very similar to Java — almost one-to-one. It’s cross-platform. Minecraft is written in Java and supports Java mods. The same goes for Vintage Story (a Minecraft clone): it’s written in C#, and you can write C# mods for it.

I see a problem ...

Thanks for the great answer! I hadn’t thought about the performance cost between the WASM and engine boundaries.
No, this question isn’t about any specific modding ideas — I’m a developer (but not a game dev). I'm just curious about how things work in the game development world or maybe I should say ...

Hi, I didn’t find a better place to ask this question.
I have a short technical question for the developers:
If you had to create the modding system again today, would you prefer to use WASM instead of Lua, or is Lua still the better choice for Factorio