Hi All- Thank you for your input! Your generous and quick responses confirmed much of what I was thinking. Here's where we stand now:
The bubble tore open, presumably from the weakened integrity. A smallish amount of water drained out.
My LL did contact the HOA (as renters, the HOA won't work directly with us, just with the LL) for advice on getting the upstairs guy to cooperate. The upstairs landlord did some kind-of-hilarious-if-we-weren't-talking-about-my-house posturing (My dad and I will be by next week to take a look kind of thing), but my LL was like no- professionals, the kind that are bonded and insured, and now.
The upstairs LL and my LL's handyman came over last night to inspect the damage. Verdict: surprise! There *is* a leak! Handyman seems to think it's the pipe supplying water to the toilet. They went upstairs to inspect that home, and then the handyman came back down and told us that both units have water damage, and that the next steps are that the landlords need to talk and decide who is going to pay for what, and if upstairs LL wants to go through his homeowner's ins. As per the handyman, until he receives deposit/payment for the work, he's not going to fix it. He can't fix our ceiling until he replaces their plumbing. I asked if turning off the valve to their toilet would stop the leak in the meantime, and was told NO.
So where I stand is: under a hole where the soggy drywall was removed last night. I could live with the inconvenience of an ugly hole, but:
1) The leak is still there, and the bucket I had to catch it now is ineffective, because rather than running down the intact bulge to the lowest point to drip it now drips along the entire length.
2) Handyman said upstairs LL is "going out of town on business until Monday", and said he definitely wouldn't know before then what he was planning on doing. I was also given the impression that upstairs LL still doesn't think he needs to pay for damage to our house, and is generally going to drag his feet on this.
So my bullshit alarm fired a few times last night, and I'm hoping you will again be able to help me.
-What is a reasonable time frame for this sort of repair to be initiated and completed? Both for the leak and the drywall replacement.
-Am I nuts to think that it's not okay to leave the leak until Monday-at-the-earliest?
-What can I do to make this go faster? I do believe that my LL understands that this is a problem, and wants to fix it, and I don't want to be an a-hole tenant, but the money conflict and insurance questions are a big fat load of not my problem.
Thanks!