IIRC Changed can fire for hidden properties, but I’m not sure if you get that error for those properties (presumably you do). This is probably a duplicate of other topics about that.
Yeah, unfortunately there’s no great workaround for this other than just explicitly whitelisting what properties you want to copy or using pcall to blacklist bad properties (cache whether each property could be successfully set in a map by attempting to get/set it in a pcall first).