I already mentioned several time on this Housing forum that overall Japanese server technology is way behind the standard.
SE is pretty much the best you can find among Japanese gaming companies (just look at the how bad Capcom's multiplayer mode in their games)
Chinese and Korean are far more advance than Japanese
Guess what?
Genshin Impact is made by Chinese.
I really don't know the purpose of this topic since Japanese never have the same technology and skill (requires time and experience)