I watched it again in full (on
@His_Cifnes prompting

) and enjoyed it even more, with less complaints all around from me, even on the drum choices.
A thought briefly crossed my mind, that it would have been nice to hear Keiko’s voice within this context. Though we’ve heard her briefly sing impromptu, a cappella (at anime shows, though miked) and with/ without monitors before, but that’s usually been with Kalafina at different times (during interviews especially, where there's no sound setup).
We (or at least, I) haven't really heard
FictionJunction sing fully acoustic and un-amplified before, like they did for this Tiny Desk. They otherwise always have mics and are using in-ears when performing or during on-stage/dress rehearsals, or at least using floor monitors (wedges) during rehearsals for lives.
No reverb (often a big part of the heightened perception we have of their voices in live videos) no playback elements enhancing sections, just human-produced sounds, blending and clashing together, in different ways.
We really got a sense for their vocal blends (who blended better with whom), and how challenging it is to blend 5-6 different singers with different styles and voices, as against 2 or 3.
Who is more used to singing unamplified (projecting their voice) and who isn't, who is restrained and who isn't (cough, Kaori

), and how their mic techniques and awareness are put to the test when their not holding the mics, and can't hear how they sound through monitors. Notice how they often had to lean back or turn slightly (Emiko with her big voice) to hopefully avoid blowing out the mic in the recording.
I think if we had more songs with just 2 or 3 singers (including lead) we would have had an even better appreciation for the vocals (I would have really be curious to hear a Joelle singing "Vice Versa" (with LINO LEIA backing her) or Kaori singing "Fake Wings" (with Yuriko backing her), in this setting.
Oh, and like I said before, a KOKIA or Kasahara, backed by Yuriko and Joelle, singing any song (acoustic version), would have been delightful, because they have the chops for true projection and precision, without amplification.