"VEB ChessMaster", I see you copied 2000-27ff from the other set, lucky that it works this way =)
I think the rom is a bad dump, or it's a rom from another computer and robotron.de misplaced it.

By the way, VEB = Volkseigener Betrieb, right?
For example you have a company "Blah Blah GmbH", then you wouldn't name the product "GmbH Chess-Master"

HD6301 emulation was improved recently, yes you'd have to copy the changes over if you want to use it on MAME 0.215.
I don't know if MESSUI requires other compile tools, but for the newest baseline MAME version I think you need at least GCC version 7. This comes with the negative side effect that it won't work on Windows XP anymore.