Ahaha, sorry, sorry, anyway to address your points: for December it's because (correct me if I'm wrong) isn't there a Comiket event at the end of the year? Again, correct me if I'm wrong on that point; second, regarding the game not finished it's in that same tweet where he posted the pic, Diisuke apologizes to another user for getting their hopes up as far as google translate goes, so that's where my assumption came from. As for translating in itself, yeah, it's wise to wait if some patch gets released, although, pardon my ignorance, but couldn't someone extract the game script and translate the text, then after the patch comes out do a quick check to see if some lines are changed (though usually they get released for fixing visual glitches and such)? Again, pardon my ignorance in this regard.
About K3 yeah, it hasn't been proofread but so far there haven't been complaints regarding the translation though there may be some grammar mistakes or such, but I'm not really the best suited person to talk about that.
Finally, regarding the translator himself it's truly a pity that he hasn't been answering the calls, but oh well, we can only hope, and though he had been missing for three months during translation of K3 he should probably know about the possible release of K4, who knows, maybe he'll come back and start working on it, but again, that's just wishful thinking.
Thanks for the quick answer anyway and let's hope that if not him, some other talented translator will decide to work on it when the time comes.