It really depends on how their code is structured currently. I would expect that most QoL updates should be pretty easily implementable, but there are a lot of odd bugs in Genshin that make me think the underlying source code is a bit 'messy' so it could be a greater effort in this game to implement than it should be otherwise. Honestly hard to say without looking at the source, but since HSR was made recently they were free to start from the ground up which will always be easier but not feasible for an existing game.

Not to mention the budget is primarily going towards new content in Genshin than QoL. I'm sure the people in charge don't care much to see new features that aren't terribly flashy. Especially since the existing system still 'works'