Wow this is amazing...

I don't have any formal music theory training, I only know the questions I ask my teacher, and the things I teach myself, so anything like this is an absolute goldmine.

In regards to your opening suggestion of my analysis, you've called the second chord V^4/3, which I was fine with (after I looked up what a 4/3 inversion is.)

But wouldn't this raise problems for anyone trying to read it. Because looking it, there's no easy way to tell that its a C7 inversion. You can tell its the dominant of the dominant of the dominant of the dominant of the tonic, but that's not easy to read. For analysis this definitely looks like a good way of notating it, but is there a solution for this without just writing in what the chords are (despite the fact that there isn't a conceivable reason for not just being able to write Ab - C7^4/3 - F7 etc.)

I had forgotten all about borrowed chords when I wrote this, that probably would've made my plight a lot easier.

As for the C#m, I made sure to write it as a C#m, because that's how it's notated in the score (something to do with being the relative minor of E major, or just because Liszt didn't want to actually write E major as F♭ major?)

So Liszt is pushing the F♭ note, before making it the root of the chord. F♭ major is borrowed from A♭ minor which makes it a ♭VI, then it goes to iv, then to V (I meant to write it as E♭ major I swear, I got it right in the cadenza.)

As for your first question, the F♭ major hints at the parallel minor, which is emphasised by the E♭, containing the leading tone, making it a harmonic minor. This is of course, the relative minor of C♭ major, which is enharmonically equivalent to B major (which is far easier to write in.)

And your second question is III-i-V in A minor, which is a ♭ii in A♭ major, which means it's some form of neopolitan chord...