When asking around on those forums, did you perchance find out whether building a sheet for Roll20 is allowed in terms of gaming license, authorization from publisher, etc? The Roll20 will ask before posting any new sheet whether you "have authorization from the game’s publisher to make this an official sheet on Roll20 with their name attached". Even though the Official Mothership sheet is in the community sheets repo, I guess we should not go tamper with that unless authorized to do so. There is however a non-official sheet by some Adam Bell, which with his approval could be updated.