NOTATIO

A very interesting vertical position of the first of notes, where at the same beat we have two voices + clef change! I believe this was how Messiaen wanted to be written, and not done by editor:

Its interesting, but of the many ways it could be handled, I think he picked the worst and the editor should have intervened. The treble clef notes in the left hand are not something new as the notation makes it appear, but continue from the four upper notes in the first part of each measure. Better that they be positioned under the corresponding notes in the right hand.

I think the most interesting aspect here is the accent, which affects only the 16-note, despite the fact it is the same note found in the second voice (as thinking orchestral).

No one would think that the accent pertains to the chord on beat one, and I think that the situation is the same on beat three. But if he were concerned about that, the he could have written: