Yes, of course it is! That’s not a package provided by CentOS. Use the packages provided by your OS, unless you have an extraordinarily good reason to do otherwise.
We have no experience with that package and we don’t test with that package. It is not expected to work without modifications to the Webmin and Virtualmin configurations, and you should know what you’re doing if you go down that path. It is not a drop-in replacement, and it is not a bug (in Virtualmin or in MariaDB’s packages) that it doesn’t act like a drop-in replacement, it looks different (paths are different, filesystem layout is different, package names are different…you can dump/restore databases across them, but they are not easily intechangeable).
And, if you must install from third party sources (against our recommendation) you cannot do it before installation of Virtualmin. Do not pre-install any software (including from CentOS), especially software that Virtualmin depends on in its yum groups or interacts with. Let the install script do its job. Then, if you need to customize what packages and versions are installed or add more packages, do so afterward. And, if you’re considering adding third party repositories (including upstream provider’s packages, like this one) do so only after understanding the implications.
I don’t know how to be more clear: We can’t test every combination of software and we can’t keep up with all the differences (paths, log locations, file names, service names, package names, etc.) that are possible. The possibilities are effectively infinite, and our time is very much finite. We test our supported distributions with the packages we install from the OS vendor repositories (and sometimes with some optional other repos that are semi-official like SCL or EPEL). That’s it.
There’s nothing wrong with the CentOS MariaDB packages, so why are you so insistent on doing all this extra work?