BUR #16936 has been approved by @evazion.
create alias welt_yang_(honkai:_star_rail) -> welt_yang_(honkai_impact)
rename welt_yang_(honkai_impact) -> welt_yang
They're both the same character it is confirmed by in-game dialogue and content from Honkai Impact that Welt came from the Honkai Impact universe and is trying to find a way back to it during the events of Star Rail's story so i see no reason why both should remain separate
here's a few pictures for proof https://imgur.com/a/t5ANEDY all of these are taken from here https://honkai-star-rail.fandom.com/wiki/Welt/Lore which is the original source used to split him