Why Jāhī and not zyhī?
Targārien ends in -n and therefore is a Terrestrial noun, thus it uses the Terrestrial/Aquatic possesive pronoun "jāha,-ys,-or,-on", while "zȳha,-ys,-or,-on" is used for Solar and Lunar nouns being the possessors.
So I have a question. Does something similar happen with the words jevi anbd aōhi?
No, since jevi is 2.pl and aoohi 2. sgl.
For 3. sgl. there are two posdible forms.