There are two questions here: general one first, then the specific one.
Rolled chords: how much flexibility in the rhythm?
A lot. The typical assumption is to play them very quickly, but musical context can dictate otherwise. For example, consider the rolled chord in the penultimate measure (62) of Chopin's Etude in thirds, Op. 25, No. 6. This chord is generally rolled quite slowly to help dissipate the energy of the rest of the etude. The Lento marking is also a major indicator.

Pollini recording from m. 58
On the other hand, the rolled chords in the Chopin's Op. 25, No. 5, are clearly intended to be rolled quickly.

Pollini recording
How should the Beethoven/Liszt transcription be played?
Glenn Gould version
This is certainly acceptable, but extreme, and does take some getting used to if one hasn't heard this approach before. Gould in particular was oft criticized for interpretations that pushed the boundaries of what was/is considered acceptable.
Note that Gould never breaks time. The melody always in right on the beat. In m. 7 his rolls are quite fast.
Michel Dalberto version
I don't think he's rolling the chords at all. Instead, he's playing the lowest octave, picking up the remaining notes in the next chords. This is also a perfectly fine way to do it. Note that in m. 7 it sounds like he's not rolling the chords. That's amazing and makes me question my ears.
How I would do it
I wouldn't roll the chords. I would break them into two parts, treating the lowest note as a short of grace note and then playing the remainder of the chord. To me, this is closest to Liszt's intent: the bass, and everything else.
For the chords that are not marked as rolled, but which are too big for my hand (e.g., the final LH chord in m. 3), I would do a true, fast roll. For measure 7, I would play the lower two notes with fingers 5 and 1 (rolled if necessary), and then cross over finger 2 for the topmost note.