Thank you, @ahoeben, for developing this plugin.
I installed the latest development snapshot (v7.0.0-2021-01-05T11-45-39Z) and ran through a couple of stl files with ArcWelder activated. I was able to slice the files but when I tried to save the generated gcode, I received an error:
Exception: Unable to write to file Test prints for ArcWelder-Snake: Command '[<<snip>>]' returned non-zero exit status -11
So, no gcode file was available to review and I could not check if G2/G3 code was generated.
With ArcWelder option unchecked, normal gcode files were generated and the file could be saved.
AWplugin v7 cura.log