Hi,
the official documentation of postgresql 12 state that the build should be done with Windows SDK >= 8.1. In fact state this:

"64-bit PostgreSQL builds are supported with Microsoft Windows SDK version 8.1a to 10 or Visual Studio 2013 and above."

I see that on run.cmd of pgwininstall there is this dos batch code referring to SDK7.1:

IF "%~1"=="1" (
TITLE Building dependencies
IF "%SDK%"=="" SET SDK=SDK71
CMD.EXE /C %ROOT%\build\helpers\dependencies.cmd || GOTO :ERROR
)

Also in the readme.md of the pgwininstall repository says that these points are required:

"Microsoft SDK 7.1 or MSVC2013 for build PostgreSQL"

Also the last releases seems to stop on 11.6 release.

I'm wondering... is pgwininstall compatible with postgresql 12?

Thanks a lot for your work!, this is a very useful proyect to make easy your custom installer for windows.