I haven't looked at everything, but in the first measures, a couple of gross errors stand out.
The chord marked 6VII at the end of m. 1 is actually a V36.
These are errors for those who understand them as such; I am comfortable with this way of interpreting them:
when I was doing exercises, in the beginning I had two little mirrors: one was the written bass, and below it was the real bass, the one that determines the harmony.
So if I take, for example, the 6III and I am in C major, automatically if I have written E in the bass, the root of the chord is C.
I understand what you mean, but let's take, for example, the 4_2 V; I start from the V degree of a hypothetical key, let's say G major:
so D, I go up a second (D-E), I go up a 4th (D-E-F#-G), I get D-E-G, which does not correspond to the actual harmony that constitutes this chord (without the 5th, B, of the chord itself).
If I write 4_2 IV (moreover, having the IV degree written in the bass, C), I start from C and go up a 2nd and get D, I go up a 4th and have an F#, still without the 5th (in this case) I have D-F#-C, exactly the 3 notes
fundamental for the constitution of this dominant chord in 1st inversion [3rd inversion/3rd relative], the D which is the root, the F# which is the leading tone of G major, the C which is the seventh of the chord.
You see that it all adds up, both the written note (and real one, C), and the distance between the notes themselves, which corresponds to the numerical [notation], there is a logic.
Then there are those who feel more comfortable with the numbering as you have highlighted it, like almost all the other forum users (which I have been able to see), but for me this way of interpreting everything does not cause problems; on the contrary, I even find it more intuitive and direct.