Wasn't the glossolalia (speaking in tongues) thing supposed to be languages that the oracle did NOT know? Like the holy power of their god/spirits were speaking through them?
The mechanic doesn't seem to fit the flavour of the class. How about the benefit being that the oracle can pass the condition to opponents in combat, disrupting their ability to communicate with each other? Or a confusion effect?
I got it. How about DC of 10+Oracle level+Cha mod and last 1 round per oracle level. It stops opponents from communicating with anybody as everything they say comes out nonsense. Enemy spellcasters who fail their save cannot cast spells with verbal components.
Anybody actually playing an Oracle?
I am currently playing an Oracle Level 4 in a friend's Starjammer Campaign.
The curses all carry a blessing, and in this case, you get to know and speak that language.
The idea of disrupting other spellcasters is too powerful for a curse in my opinion.