Hello, I am the audio guy of another team and I had the exact same problem with the audio layers being out of sync. Did you use FMOD?
Hi! We used the audio tech built in the Godot game engine. It doesn't seem to be fmod.
But thanks for the comment. That would mean this is not a Godot specific issue.
We would be interested to know if you fix it. (and we will inform you if we find something too, but we don't expect to spend time on it for now)
We never fixed it and there is no know fix to the issue until now. My team looked everywhere and only found that for FMOD the audio gets synchronization problems in the web build. If you use the app everything will be perfect. I thought it was only an FMOD problem so I thought about switching to WWISE or another engine, but playing your game and communicating with you have shown me that it is something that will happen with web builds regardless of the engine.