The allegretto begins with a parallel symmetric period lasting from measures 1-16 with a HC at m. 8 and a PAC in m. 16 (in the key of e minor). This period is then repeated with the same cadential structure from bars 17-32. The only difference is that there is a HC in m. 32 instead of the PAC. The first phrase is again repeated, but the octave differences are inverted (it's high first, then low, on the repeat). The rest of this section until the Maggiore is a a huge set of cadential extensions turning into a terminative phrase. We end on a PAC in E Major.
The Maggiore is in the key of C Major (CHROMATIC MEDIANT!!!) There is a HC in m. 4 with the dominant seventh chord. Measures 73-75 seem to be tonicizing a minor, while G Major is tonicized in the Measures 76-78. Measures 79-88 is just a long phrase group that keeps taking a motive and displacing it in different keys. By the time we reach m. 89, we're back in C Major with the opening motive of the Maggiore. There is a huge HC at m. 100, and the coda repeats this last phrase and tags on a cadential extension to end the piece in e minor on a PAC.