Soundtrack Manager has no default parameters in its functions, so you likely wouldn't see this particular issue - at least, if in fact I correctly understand what the issue is. For the record, Dualtechs and Actor Icons don't have default variables either. Battle VA Manager does, though.
I could rewrite the plugin to avoid the default parameter issue when I have the time, but it's weird it's happening in the first place. And if you want a refund instead of an alternate version, then... I don't know how itch.io handles it or if it even does, but I can try to look it up.