The purpose of the engineering test is to characterize the performance of the AO system under different conditions and also to see the effect of changes we make to the system.
Night time is required because it's hard to see magnitude 12 stars during the day. No, it's because we don't have any way to reliably "simulate" the atmosphere.
As always, I reduce and analyze the data and report the results and conclusions to the AO team. Previous results are on the AO characterization webpage.
I am in the process of writing two papers for publication on my results.