I use 2 3 in the fast trill, then change to 4 5 when there are the d sharps below with the thumb then to 3 4 for the rest of the section.
The reasons are that the fast trill should be as fast as possible (I tried 2 3 4 but it didn't work out well); the d sharps with the thumb should be light and not accentuated, and playing the trill 3 4 would probably make your thumb too strong. The stronger thumb is the reason why I shange for the next section where the thumb is playing the melody.
By the way, notice the change in trill speed after the cadenza and before the introduction of the melody in the left hand! This trill should, as I said, be really as fast as possible and could well last for 5-8 seconds, and then changed back to 32-notes in time with the quavers in the melody.