I additionally looked at f3r, which has four paragraphs with the following first and last words:
tsheos... cthom
pcheol... qokeey
tsheoarom... sam
pcheoldom... am
Again, all the paragraphs begin with a gallows. It's tempting to go on a flight of fancy and imagine that the last notes, with -m on three "parts", have three notes of the same pitch class, maybe even with the tenor and bass lines in unison (-am), and the soprano an octave above (-om), and the alto line in between, maybe a fourth or fifth above the bass. This would be, I believe, historically appropriate.
But alas. I did the simplest statistical test, comparing frequency distribution of letters in paragraphs of different sizes, for three sets of "related" paragraphs - You are not allowed to view links.
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Login to view. - with a negative result. In some folios, some letters are proportionally more common in longer or shorter paragraphs, but the patterns do not hold across the three folios.
For differences caused by rhythm in particular, I suppose you could say that maybe the pattern would reverse depending on the meter of the piece. For example, in modern notation, quarter notes are more common in the faster-moving part of a piece in 3/2, but more common in the slower moving part in a piece in 3/8. We could also say that maybe the rhythm is not specified for every note, only when it changes, or something. But that's definitely adding complications.
Perhaps the patterns we do see are from pitches, if different parts have different smallish ranges, or simply tend to hang out on different pitches. The letters which vary in frequency the most between paragraphs on the same folio are: c and h, strongly, and e i l, less strongly. In f3r, m has this characteristic too somewhat.
If lyrics are present, I think they must be present on every note. Is there any small set of segments, exactly one of which is in just about every word?
Overall, this is evidence against the music hypothesis. It's not impossible, but there are fewer ways for it to be possible.