https://bugs.winehq.org/show_bug.cgi?id=48006
--- Comment #43 from Andrew Church achurch+wine@achurch.org --- It looks like only one additional Proton patch was needed: https://github.com/ValveSoftware/wine/commit/40485c3435b650ffa727baf15874bd0...
With that patch included, the ff14-launcher-9.x branch now successfully runs the launcher.