At this point I've seen the data from all of the telescopes for the 1/31 event and I cannot say for certain whether we detected anything or not (which is unfortunate, because that means we can't reduce the timing error bars for future events yet).
The main difficulty is that most telescopes (in particular, the 3 largest telescopes) had only one night of observation covering about 6 hours at most, so there is not complete overlap of the 3.91 hour light curve. What overlap there is comes from high airmass or deep twilight observations.
The only solution to this problem is to observe for multiple nights, to get a fiducial lightcurve to which to compare. This was done at MRO and the Faukes North telescopes and results are still ambiguous at best.
Much better will be when Haumea is up for ~10 hours in a row in the next month and we can observe 2+ rotations to have a direct comparison. With luck this will make a big difference.
In the meantime, we are trying to construct multiple-rotation light curves by stringing together data from different observatories. This stringing only works if we all use the same filter. In the past I had no recommendation for filter, but after these events I think I will suggest R filters for everyone to all ease of comparison.
Over the next few months we will collect enough full light curves with and without events that I believe we will be able to go back and find the event in the 1/31 data. We might even be able to find it when people do more careful reductions.
In the meantime it is now time to start focusing on the 2/18 event. It will be visible over most of Asia and we know of several ~2m telescopes that are attempting observations.