And if you have to make major changes to the code, just to turn around and have to do it over in a couple years might not make sense.
It's for sure wouldnt need major changes. EL 8 and 9 doesn't different a much, but few catalogs could be in other places, but almost all used packets are the same... Most if not all will be at the same places.
And Centos Web Panel used many scripts and others software packages or source, and it build own php, so its require a little of test, moreover there is so much el systems now: Almalinux, rocky Linux, RedHat Enterprise, Centos Stream, OracleLinux etc.
So it require a little more tests, and eventaully write differences (up now i guest when i look install script there was none for wchichover but could happen) per system or looking step by step why smth not work and how repair that.