no problem, I'm glad we figured it out - perhaps someone interested might fix the engine since it's open source.
it seems that in parser.c in EditMode function the engine should infer castling rights before BoardToFEN,
where kings and rooks are in their initial positions. it's funny that Beowulf supports setboard <fen>, but that is protover 2 command,
so the GUIs don't know it's available.