So lets consider this... her mother was slain by humans whom than stole the last tear she shed in order to protect her daugther.
That aside she stated she was indifferent to the humans struggle and only reclaimed what she considered to be her heritage when given a chance... she made a deal with the peasant... not an alliance, and even if the MC is betraying and following both gods... I think his main interest further down the line is to prevent any actual combat situation, as weirdwood and himself would certainly perish in that struggle
Elves are very protective and secluded... in general they worship nature itself or a deity related to it.
some Elves worship the moon others the sun or the world tree.
But the lore we get from any source clearly states that they don't worship the gods of humans... and are proud of that fact.
So I don't think Quetesh has many followers among elves (maybe a few rebels like Liandra, but she didn't rebel against the gods).
In a polytheistic world there likely is such a goddess of for example nature and hunt, which is majorly worshiped by elves.
A deity that told her kind to isolate themselfes from humans in order to avoid getting sucked into the devasting battle of Nergal and Quetesh