Ok unchecking/checking “dont include editor content in build” might force UnrealFrontend to update…
Additionally, I unchecked all cultures except “en”.
If I go and uncheck all settings, it clears the error; reenable the settings including stage base release, and the error pops up, but I uncheck stage base release and uncheck/recheck include editor content, and now it works…
As for figuring out what’s going on with linux building, I cooked content in editor for linux shipping on my windows computer and rebuilt, made no difference. I have a laptop I dualboot linux on now so I guess I’ll just make linux builds from there if cross compile can’t be bothered to compile all shaders for all platforms and RHIs.