To reiterate, the only sheets available are those that the fans created. The Roll20 staff by and large aren't the people creating them. If a sheet is nonexistent, it is because someone familiar with the game system hasn't created one yet. If you're looking for a character sheet which is currently unavailable, you can either make a request and hope a fellow fan of the system creates one, or you can learn the code/scripting to create one yourself (possibly the quickest method, plus you learn some coding skills along the way!)