Ditto. Tiana was definitely not 'princess' in Greek. A princess in Greek would be Basile/Basileia, Despoina or Ho Turannos (which actually meant 'sovereign ruler' and referred to the entire royal family, not just 'princess'). And I've never seen anything like Tiahna in Maori.
There's te anake 'the alone' or tinana 'body' or tàriana (boar...shame isn't it, such a pretty name it would make but you don't want to name your daughter 'boar') but the only thing I've seen close to Tiana is Karaitiana, based upon the English word and meaning the same as 'christian'.