What I would recommend is:
- first Geoconvert in Level 9 only (or Levels 9 & 11 if you want - this should be a rather fast process) to check everything runs smooth.
Launch higher levels afterwards, as a separate batch.
To do this, you just edit the TMC file with Notepad (or better, Notepad++) and comment (add initial // to the lines) blocks for levels you want to ignore.
Since there's little hope the Geoconvert tool will soon (ever?) be fixed, an idea would be Aeroscenery to automatically generate separate, Levels-groups-specific TMC's for manually launching Geoconvert => 1 TMC for Levels 9 & 11, and another for higher selected Levels...