I also found a term tirata (or tirade), which I am not sure can be applicable to Chopin.
According to Artopium Music Index, tirata is a
baroque ornament consisting of a long scale passage
Another source, that is actually referenceable, "Musica Poetica: Musical-Rhetorical Figures in German Baroque Music" by D. Bartel has
Tirata: a rapid scalar ...
It's commonly called a roulade, or sometimes fioritura from Italian "flourish." In his later compositions, they're often more elaborate than just a scale.
It makes no sense to call it a tuplet, unless it's Ferneyhough or Berio ironically quoting Chopin.
As marcelloverylongname commented, this is a run. The notation is easier than trying to notate 29 notes into 5 eighth-notes. ( 6-6-6-6-5 ? ugh)
Given that this is in the middle of the piece, in 3/4 time, with only an eighth-note in that bar, you should make the run come more or less close to using up the remainder of the meter in that bar. A ...
The dotted minim/half in the lower stave shows that 6 quavers/eights fit. So the "2" means "2 in the time of 3". It indicates an irregular group of notes; usually a higher number of notes have to be played in the time of a lower number, and thus quicker than notated; here we have the less usual situation where a lower number (2) have to be played in the time ...
That is a duplet. It works like a triplet, but instead of playing three notes in the time of two, you play these two in the time of three.
Another way to write this is by using dotted eights. But for example in 6/8 time, it's preferred to use duplets. It helps signifying how foreign the rhythm is in relation to the time signature you're in.