I just tested your change to function IsolateSelected()
It seems to work by not hiding everything
With nothing selected it adds an entry in Command history
The only way I could stop that is add:
if (Node.SelectedCount() == 0) return;
to the beginning in the toolbar LMB command
Edit:
I hope that you are not having to change your CustomCommands scriptsDid a search and global fs only being used in maybe 15 scripts, that's doable.
If so, wouldn't be easier just to recreate another FN Set in UUCommands?