Let me ask this question.
Can your problem be solved by making "sub-races" for Fiendish Dwarves, Elves, Ect? Because it sounds like that is your problem. "It used to be that I could be a dwarf with fiendish heritage, but now I'm using the generalized stats for a human with fiendish heritage, so I can't be a dwarf, so Tieflings are terrible"
But, like I said, this is a trivial thing to change, especially post-Tasha. And it is something I've had to do. I had an Aasimar born to a Goliath parent, that meant I had to adjust somethings, because it was an Aasimar, but that wasn't too bad to actually do.