Krom is used at least for development because of fast build times, but it should be fine for production deployment as well, as long as you don’t need to publish to consoles or to iOS.
You might get some more efficiency out of the C build of the game, but there was a time where Krom actually ran faster than the C++ build ( that was before we switched to compiling to C I think ) so that could depend on the game.
Also be aware that WASM doesn’t yet have full access to the Armory API. It is actually pretty limited in what it can access at the moment. See this post.
If you wanted to write a library in Rust and interact with it in Haxe, that might be easier to get working, but either way, using Rust in Armory hasn’t really been put into practice yet as far as I’m aware, so it might require some more work to get going.