There are a lot of reasons to hate choices Genshin has made surrounding cultural representation and implementation. Hell, I'm south asian so despite my love for Sumeru it was agonising at times.
However, getting mad at localised pronunciation is so brain dead and just an excuse to get mad for no reason. It would make absolutely no sense for characters to speak in an American accent and then randomly dip into an Arabic or Slavic accent like what. The way the JP and Korean VA's pronounce his name isn't to be more accurate to its true pronunciation but simply because that's how it got localised in their languages.
Also side note, Ajax isn't even an originally Slavic name its Greek so why is this person even discussing a Slavic pronunciation as the correct one