Huzzah, I've reached the end of June 2012 without problems, so looks like the fix worked.
There's one small problem in that the phantom games are STILL listed in world.dat:
...even though the rest of the schedule data has been updated for the new season. Oh well, just more dead bytes for world.dat, I guess. Shouldn't break anything, at any rate.
In case you haven't junked the league yet and are interested in the fixed file, endgame, send me an email through my profile (or PM me your email address, whichever you prefer), and it's on the way to you.