trying to find an on-line Hawai'ian translation for 'thank you'

Easy-peasy
Mahalo.

If you want to get really fancy :
I am grateful for you help = ho'omaika'i i au i kokua mai
(Pukui Elbert Dictionary)
but nobody expects you to know that unless you're a Native speaker!

Mahalo and kokua are seen and used a lot even by haoles.

Mahalo is a general thank you. One lady, visiting Hawaii kept seeing the word Mahalo on the refuse containers in McD and Burger King et.al. She thought it meant rubbish until a kind soul told her the real meaning.
You might see a sign in a bookstore asking you to return books to correct shelves ending with :"Thank you for your kokua" (co-operation.)
That's it, I'm pau (finished)
wow