i just realized something, issa might be born from an elf that lost her protection... or maybe a nun that was granted blessings of the moon. (refer to dialogue with the infernals when giving up issa as an offering)
so that could mean the nun or the huntress could give birth to a smarter kobold than normal, or maybe another kobold variant.
edit: oi i said could, not preferable... but with that said, i don't think there's any issue with the nun birthing smarter kobolds.