I apologize for any confusion it may have caused, however the info that Jaap has given is actually incorrect.
FOSSBilling does have support for Control-WebPanel (CWP for short, previously went by CentOS Web Panel). In fact, the integration for it has existed before the FOSSBilling project itself did.
It is true that we don't currently have team members who use CWP and as such it's not getting regular tests however, their API is also not receiving any changes as far as I can tell so it's unlikely that the integration will stop working anytime soon.
Either of you can verify the list of supported control panels at any time by either:
A) Checking the list of supported control panels.
B) Checking what control panels we have setup guides for, CWP being one of those.
I am aware this is meant to be just a billing software, but to see addons to support webhosting and some of the most commonly used open-source products would be very nice.
I'm not entirely sure where you're getting mixed up about this, however FOSSBilling is a billing panel with it's biggest focus being on web-hosting and other digital products. The website actually says "Free and open source
hosting automation". Also just FYI: CWP is not open source software.