I made a copy of the Steam-installed Proton 4.11 into my compatibility tools.

cp ~/.steam/steam/steamapps/common/Proton 4.11 ~/.steam/steam.compatibilitytools.d/Proton-4.11-alt

In the copied Proton folder I put in a compatibilitytool.vdf file

{
  "compat_tools"
  {
    "Proton-4.11-alt" // Internal name of this tool
    {
      "install_path" "."
      "display_name" "Proton-4.11-alt"
      "from_oslist"  "windows"
      "to_oslist"    "linux"
    }
  }
}```

Then I downloaded the patched ntdll.dll.so (second link) from

https://github.com/ValveSoftware/Proton/issues/175#issuecomment-600465929

and put it in `~/.steam/steam.compatibilitytools.d/Proton-4.11-alt` replacing the existing `ntdll.dll.so`

I restarted Steam and picked my custom compatibility tool (Proton-4.11-alt) under MH:W properties.

The game worked just as well as with GE 5.2, I was able to go on multiple hunts and play with others.