As linked in WineTerroirist, there is a nicely done, if a bit superficial, article by AmandaBarnes on Croatian wines:
CroatianWines .
Interestingly, she makes no mention of Tribidrag (Crljenak Kastelanski). She only labels PlavicMalic as a son of Zinfandel. That's it.
She refers to the grape Malvazija Istarska (Malvasia d'Istriana in Italy) as the 2'nd most planted variety. This variety is genetically distinct from the other Malvasias in the World. It's a variety that I think makes lovely wines & should be planted all up&down the Coast of Calif.
Probably about the best source for Croatian Wines is FrankDeitrich's BlueDanube Wine Imports ( BlueDanube ). They do DTC sales, rare for an importer.