Tempy may well have been your Tempy Jane's given name but it is essentially a nickname for "Temperance". This was one of the "virtue" names for females (like Charity, Prudence, etc.) in use during the 17th century until the early 19th.
Tempy was the name of the black cook played by Hattie McDaniel (also of "Gone With the Wind") in the 40's Disney movie "Song of the South", which for dubious reasons of political correctness has joined the wonderful "Amos and Andy" TV episodes on the dustheap of entertainment history. Bet you and 95% of the people on this board have never had a chance to see either one, and it's your loss.
(Zippa-de-doo-dah, dem lib'ral white folks is sho' tetched in de haid!)