Thanks for more info!
So I assume there is some JavaScript error on your Chromebook that prevents the page itself from functioning correctly. Unfortunately, without any knowledge what that problem is I wouldn’t be able to address it. Maybe somebody else will face it as well and will be able to poke deeper.
Your Linux setup seems fine from that description. It would be nice to see the entire error log though, could you show me what it prints from the top? From what you’ve already shown, it’s clear that the Godot runtime is operational, but the synthesizer library is not loaded for some reason. That’s very strange, and the only thing I can think of immediately is that it’s some permission issues.
Make sure that the .so file that comes with the Linux version is accessible by the same user who runs the Bosca executable. A library file like that normally doesn’t need an execution permission, but maybe it does in your case? Worth checking this as well. The ZIP already should have correct permissions otherwise (sans the user, of course), but if you unzip it on one machine and then copy to another these permissions can get lost in the process.
