after few hours of torture i got it also running. ubuntu18.04, wine 5.0.3 (from source), winetricks (from brew; version 20201206). but my config diffs a bit.
at first i had alike problems as Bloodiko, SkylordsRebornUpdater.exe only showed a black.screen with two strokes in the upper left corner. no invisible buttons to press. this i was able to solve with the brew.version from winetricks. my previously used (manuel installed) winetricks seems to borge the dotnet461 installation.
after i got winetricks from brew installed, i re-installing dotnet461 (ll b three packages which gets installed) and had finally the Updater-screen working, but Battleforge.exe was still crashing. After switching to "win8" and enabling virtual.screen via winecfg it was finally able to sign on.
- finally i can re-experience "old good memories".