There are 2 engraved stone plaques in Kion. I've translated them. We now have an Istarian alphabet! (Though J, Q, X and Z are missing).
The 1st engraving is on an obelisk (20569 / 24484):
The 2nd engraving is on several gravestones (20313 / 24623):
I don't like spoilers, that's why I don't post the translation (unless you want me to) so you can try to discover the Istarian alphabet by yourselves!