Hi,
the fact that EL9 OSes (RHEL9, OL9) are not selectable as guest OS is due to the fact that rbvmomi (VMWares ruby library that Foreman uses) is not maintained anymore and thus outdated. According to Any plans on replacing rbvmomi? - #6 by evgeni, this will likely be fixed in Foreman 3.6 by replacing rbvmomi with a fork, rbvmomi 2.
No idea about your other problems, though. I have never encountered those.