But this is not the issue here. The PAPI assets in game (the objects added in scenery editor) have several properties, like offsets, spacing and pitch (lights elevation). Pitch is what’s used to set expected PAPI glide slope. If you set a typical standard value of 3° you will always crash into airport fences or nearby obstacles.
St. Gallen charts do not indicate difference in PAPI/ILS glide slopes only that obstacles are expected on final. Charts indeed set 4° glide slopes for both systems, however PAPI are giving you an effective 2° glide slope in game (at least that appears to be the case).
I have only used PAPI2 and PAPI4 in my addons but in both cases I had to set a much higher pitch than the official values for the airport. In the cases where there are evident mismatches in game the difference is clearly visible because PAPI either makes you nose dive into runway or sends you into nearby crops and house roofs. Something appears to be broken, despite possible discrepancies between ILS and PAPI that should still exist as mentioned by some of you.
Cheers