I've updated the Maskelyne maps - this is the first major revision to my original material. Originally I had placed Maskelyne on an island in the northern Mare Tranquillitatis (on what lunar maps label Plinius). Unfortunately at the time I was working from a map that didn't have the real Maskelyne labeled, and I just chose something that I thought looked good.
Anyway, as it turns out, the real Maskelyne is on the opposite side of Tranquillitatis - in the south. So after some deliberation (while working on other cultures in the vicinity of Mare Tranquillitatis), I decided to see what it would look like if I actually moved it. Here is the updated map:
I've left the older maps in the first post for comparison.