I sure don't. Same as last year, I had scripts suddenly start failing, which I tracked down to incorrect returns for mp_cost(). And eventually realized that mafia thought it was FoJ while main.php did not.
It seems the simplest solution might be to eliminate mafia's belief that Jan. 2 is FoJ. At least that way, mp_cost() will be calculated in a manner where calculations for number of casts won't fail, but instead there will be unexpected MP left over (during the part of the day when FoJ is occurring). ?? I don't know.
On the other hand, it's a once-per-year glitch and is probably caused by some timing thing on KoL's end of things...so it may not be worth messing with at all.
I would think that more people would be reporting their mood triggers etc. not working as expected (as in the original post in this thread)...but so far that doesn't seem the case. Or they're just not reporting it. So, maybe it doesn't affect things enough to be noticed much?