Yeah on the spelling Ají, but Joya has a y and La Jolla does mean “jewel (spelled by someone who couldn’t spell/whose spelling didn’t match current norms)”. Sometimes it’s hard to remember that our current spelling isn’t necessarily the way someone would have spelled in the 17th Century, specially someone whose education had been centered on “spelling properly in Latin” or on “how to grab a sword properly”.
Posa could also be an apocope for posada, “inn, road stop”, but given cases such as the aforementioned La Jolla I’m happy with the explanation of it meaning wells.
ETA: Ají, I wanted to sent you a piece on the confusion caused by phonetic spelling in a modern classroom in Spain, but your email isn’t listed. Mind dropping me a line, as mine is?