Look I did some digging in the comics The Black Flash is hunting them and Barry has to protect Psych, Fuerza, amd Steadfast (IDK why cisco and chester havent named him that yet)
And at this point you might know who the first big bad is
You dont know who the black flash is heck he was seen in the arrowverse at the end of Flash S2 when zoom was taken by tine wraiths and was seen as well in S3 and on s2 of legends
The show isn’t going to do anything with black flash as far as I know. Just cuz it happened in the comics doesn’t mean it’s going to happen in the show.