I have no idea if this is something that MusicBee does wrong and is some bug that can be fixed.
One possible solution that comes to mind is using virtual tags that recognize 'Ch' in the beginning of titles, linking that to a character different from the standard alphabet set, and putting that character in a language file so it will show up in the AZ bar.
(Searching the forum for #Main.ctl.JumpList# will give you some idea)
Anyway, I'll step out, since this is a bug topic, and I am digressing...