As I've been brushing up on my late medieval palaeography recently, I figured this would be a fun exercise and have been going over the transcription thus far. Here is a revision of the material you've both already covered for the first page. I've tried to bold the changes from the final suggestion I could find in the thread, but my apologies in advance if I've missed something. The italicised words relate to notes at the end (numbered according to the given numbering of the words). If l have time I'll have a look at the second page as well, but I'm not sure exactly how soon that will be.
[de] mensura commune dyametri terrae et de eius ambitu hoc
spectat ad geometriam et non astronomiam. Ex istis in? […]
-tł notitia totalis presentis tractatus spere materialis non sit omni-
no pars astronomiae. Yn oppositione argumentatur quod omnia quae in isto tractatu
5 primo? considerantur in primo? considerantur in ordine ad celum et quantitatibus? et motum
eius et alios effectus inde provenientes et de istis primo? considerat etiam?
astronomia igitur. Pro ista questione ut clarius viderantur aliquae generalia circa
istam materiam. Notandum primo tale quod hoc nomen astrum componitur cum illa dictione? greca
nomos qui in latino sermone significat sicut lex[.] inde dicitur nomen astronomus
10 et est ille qui ait et docet legem de astris. Inde causa venit hoc nomen
astronomia quod significat scientiam? de astris et caetera; astronomia quasi lex astrorum
quia illa scientia cursus astrorum et figuras et habitudines stellarum circa se
et circa terram et aerem percurrit. Similiter conversionem caeli, ortus et occasus
motusque siderum continet. Pro quo notandum secundo quod astronomia sic
15 diffinitur: est scientia considerans corpus celeste quantum ad eius quantitatem,
motum et figuras proprietatesque consequentes tam in subperioribus quam
in inferioribus ex hijs. Est autem duplex astronomia: quaedam est de cor-
poribus celestibus et eorum multitudine, quantitatibus et figuris mo-
tibus ac proprietatibus huiusmodi motus consequentibus ut sunt coniunctiones,
20 oppositiones, eclipses et similia. Alia est astronomia considerans ex
motibus astrorum effectus consequentes ex illis motibus et cetera in illis?
inferioribus ut quando quis judicat ex motibus astrorum quod aliquis
natus sub tali aut tali signo, sit fortunatus aut infortunatus
vel quod ex tali coniunctione etiam? eveniant caristiae, pestilentiae et
25 cuiusmodi et illa proprie vocatur astronomia iudicialis aut astrologia
78: I assume that this is the end of the word that has been lost in the previous line. I see what looks like a t and a crossed l, but that’s mostly just a guess. If we squint a bit and read el, it might be the end of caelis?
98, 100, 117: What’s been transcribed as “primo” doesn’t really make sense to me since the second letter is clearly n not m and the superscript looks more like an e (compare the superscript o at 136 and 207), but I’m not super confident on this last point. I read p’ne, which seems like it should be something like “principale” or “principia” if we read the superscript as an a, but I agree that “primo” makes more sense in context. “Principio” is the only other possibility that makes any sense, but I would have expected a preposition in that case. (But this author does seem to drop a number of expected prepositions before ablatives, so who knows.) In either case, I've left the primo in as I'm not confident about an alternative.
101ff: Note that “in ordine ad” is a technical expression meaning “in relation to” (see DMLBS, s.v. ordo 9f).
106: Given “qntit[us]” I assume they’ve just left out -atib- as we find at 245, though this doesn’t make much sense to me here as the context seems to demand another accusative. I don’t know if we can really reasonably read “quantitates”.
119: I read that as ec[is] which, lacking the abbreviation marks, Cappelli gives as eciam, which does make some sense in context.
148: “Sermone” makes a lot of sense in context, but the letters look like tm with an abbreviation mark. Certainly were it sermone, it would be unusual for the abbreviation not to give the final “e”. In isolation, I’d be inclined to read the abbreviation as “tamen”, but given the context "sermone" seems like a sensible emendation. (Or perhaps the author felt that the context was so clear that a clearer abbreviation wasn't necessary?)
149, 172: I like fit, but it doesn’t make sense to me that they’d use a weird fi ligature and a superscript t. Instead, Cappelli gives significat for ßt.
173: Perhaps the mark at the end was meant as a sideways m? It doesn’t look like a j in this script (compare 152) and this is otherwise the same abbreviation as 182. (Although 182 is written with a ci ligature, while 173 with an st ligature.)
l. 12f: This section is based closely on a definition of astronomy that goes back to at least Cassiodorus, Institutiones 2.3.6: “Astronomia est itaque, sicut jam dictum est, disciplina quae cursus coelestium siderum et figuras contemplatur omnes, et habitudines stellarum circa se et circa terram indagabili ratione percurrit.”
l. 14f: Isidore, Etymologiae 3.27.1: “Nam Astronomia caeli conversionem, ortus, obitus motusque siderum continet…”
202: We can presumably emend “occausus” to “occasus”.
237: Q with a double hat is definitely quaedam, which seems to be a pretty common follow-up for "aliquis est duplex". I take it that this quaedam anticipates the “alia est astronomia” at the beginning of the next sentence.
250: I’d read the h as being struck through, leaving us with “ac”. Whatever the case, though, this can’t be a new sentence.
275: This looks to me like illud, but it must be something like illis, istis or whatever. 274 is ī with the abbreviation mark for 285 overlapping the bottom.