I am sure Win32::getACP() has worked some time before.

I also wrote a small C++ program which calls the getACP() function. The result was 1252 as expected.

I also had a look in the module tests (codepage.t), but they only check, if the returned value is in the range 0-65001.

It might be that something changed with the API in newer windows versions, and the module needs to be adapted, but that is pure speculation.