First of all, thank you for all the great contributions you're making.
I don't see a lock on the Shach. What are you trying to edit? Try refreshing your browser and trying again. The only comment I'd make about the way you've set it up is that setting it up as a commentary is probably not the way to go. I know it's a commentary on the Shulchan Aruch, but the was Sefaria handles commentaries is special. A commentary is a text which has no structure of it's own, but instead follows the structure of the text it's commenting on. In the case of the Shach, he has his own structure - siman:: Seif Katan which doesn't correspond directly to the seifim in the Shulchan aruch. You may want to model it instead on the Be'Er Heitiv (which has the same issues as the Shach) - set it up as an independent book, and then link the seif katanim in the Shach to the appropriate seif in the Shulchan Aruch.
As for name, My personal preference is for Shakh, but either way is fine - whether we use the full name or the abbreviation the other will just be an alternate name so people will find it whichever name they put in.