M-Files Visual Studio 2019 Extension on Windows Server 2012

I haven't seen this myself.  Why are you developing applications on a server operating system?  Have you tried with VS2022?

I would like to be able to debug while creating my VAF applications. According to the documentation, this can only be done on the host of the M-Files server since I have to attach to MFAppPlatform. VS2022 is not compatible with Windows Server 2012 so we have to use 2019. 

That's not entirely true.

You can develop vault applications and both deploy to and debug code running on another machine.  You can do this by editing the M-Files server details in the PowerShell file which deploys the application, and by installing the Visual Studio remote debugging tools onto the M-Files server to allow you to connect to it.  You may also need to open some ports.

Remote debugging - Visual Studio (Windows) | Microsoft Learn

There is an argument about whether debugging into a production environment is good practice, but it should be possible.

You may also be able to speak to your M-Files representative to see what cost would be associated with a development licence for M-Files that you could run on your machine.