I'm having trouble figuring out what's happening in the following bars of this piece in Eb major.
- Bar 4: My best guess is that this spells out an Eb fully diminished 7 -- or idim7. (The F in beat 1 of the treble clef is an appoggiatura and not part of the chord harmony.) But I'm not satisfied with this analysis. It feels almost like a dominant to me. Also, even if it were a diminished, maybe it's based off some other note as the root? Ideally something that would make this fit into music theory better.
- Bar 14: I'm lost here. It's an enharmonic Eb7 chord (with an added #4), but with C# instead of a Db, Tchaikovsky is communicating that it should be interpreted otherwise.
I filled in what I think are the other chords below. I'm more confident about these (but not 100% sure)

Re Bar 14: I had considered a German Aug6 here, but my (naive) understanding of these chords was that they only occur between the b6 and #4 of the scale in order to voice lead to the dominant. I did some more research and it turns out that Tchaikovsky (in his textbook on harmony) defines them as "nothing more than inversions of certain chords having the 2nd degree lowered". The other thing here is that this implies a tonicization of D major.
– Jack Kinsella Sep 27 '23 at 04:07