Hi, I'm caretaking a thoroughbred property for a friend at this very moment.
There are a few older words for "Prince" that sound better than the loanword
prionsa. Using these, some possibilities for "Shadow Prince" are:
Bárr na Scáilí BAWR nuh SKAW-lee /bɑ:r Nə skɑ:l´i:/
Flaith na Scáilí FLAE nuh SKAW-lee /fLæ: Nə skɑ:l´i:/
Mál na Scáilí MALL nuh SKAW-lee /mɑ:L Nə skɑ:l´i:/
Rí na Scáilí RHEE nuh SKAW-lee /r´i: Nə skɑ:l´i:/ (Modern meaning more like "king of the shadows")
Tórna na Scáilí TOR-nuh nuh SKAW-lee /to:rNə Nə skɑ:l´i:/
na Scáilí literally means "of the shadows"
For "Shadow Jumper", perhaps:
Léimeadóir na Scáilí LAY-muh-doorh nuh SKAW-lee /l´eim´ədo:r´ Nə skɑ:l´i:/
For "Dancing Shadow", perhaps:
Scáil ag Rince SKAW-lih RING-kih /skɑ:l´ə riŋ´k´ə/
Scáil ag Damhsa SKAW-lih DOW-suh /skɑ:l´ə dausə/
(Haven't got my dictionaries with me, so spelling checks welcome)
Await further input ...