Nicknames, I think, are integral to making a story and close, informal interactions feel natural. Even for the nobility and royalty. I'm only mentioning this because I read a suggestion to use only full names, which I don't agree with. :P
Hope this helps.
Avalana -
Ava, Avie,
Lana.
Trindale - Trin, Trinny.
Elva - Seems unnecessary to nickname her, but probably
El.
Patrika - Trik, Trika,
Rika.
Pethalia -
Thalia, Thali,
Lia.
Cortiana - Cort,
Tiana,
Ana,
Tia.
Fauneta - Faun,
Etta (if pronounced fawn-ET-ta instead of fawn-EE-ta)
Joanalie -
Joan,
Jo,
Lee.
Dasley - Das.
Galliam -
Gal,
Liam.
Silveren -
Silva,
Ren, Silv.
“Fairy tales are more than true; not because they tell us that dragons exist, but because they tell us that dragons can be beaten.”
― G.K. Chesterton