https://bugs.winehq.org/show_bug.cgi?id=40613
--- Comment #45 from gsd gsd.zak@gmail.com --- Thank you! Making a clean prefix and installing only .NET (winetricks dotnet48) first worked.
To be specific I did some overkill steps since I like to only have one prefix at a time if possible and to be double sure: I uninstalled winehq-staging and all dependencies using apt, used winetricks annihilate to get rid of my current prefix, then reinstalled winehq-staging and ran winetricks dotnet48, then wine WeMod-setup.exe. This worked fine.
I had used winetricks dotnet48 in my last prefix, but maybe something else I had installed was gumming up the works. Absolutely worth making a new prefix to get WeMod working again, a program I can't recommend highly enough.
Thanks again!