"These two manuscripts share many common traits: same number of folios, same justification of the lines of text, regularity and page format, same letter forms --a later Gothic book hand which is the work of the same scribe."

As Phil has noted, "libraria gothica formata" is simply the Latin expression for a any genre of "Gothic" book hand (and, I assume, would be applicable to most mss. from the early 13th c. on).

Your "Gothic book hand script" is o.k., but redundant (a "book hand" being a "script"); and the source you found at

http://dictionnaire.sensagent.leparisien.fr/LETTRES/fr-fr/

suggests that this "lettres de forme" is simply the formal name (in French at least) for "caractères gothiques des manuscrits du XIVe siècle," which is what we've got here.

As I said, this is definitely not my field --and a damned complicated one it is.

It *may* be that "lettres de forme" is the technical name within the field for this specific form of "Gothic book hand" --in which case you should leave it, putting it in quotes, with the explanation following immediately.

But I've never seen it before (as opposed to, say, "bastarda" which is also a technical term for a specific form of late medieval script), so, lacking any English source which translates it with an English equivalent, I'd say translate it as "letter forms" with the specific clarification immediately following.

Here's something on that "bastarda" script (Fr. "lettre bâtarde"), a term which is in common usage among palaeographers of any language:

https://en.wikipedia.org/wiki/Bastarda

But there is no wikipedia entry (even in the French wiki) for "lettres de form" --and my best guess is that that phrase is *not* a specific form of script in common usage (among palaeographers) like bastarda is.

I could be wrong.

Caveat emptor.

--------------------------------------------------
Note added at 2 days28 mins (2017-08-07 17:25:54 GMT) Post-grading
--------------------------------------------------

@ B D

Yes, quires is better --though folio has the same sense, it is more often used in describing printed books; and réglure is certainly ruling (the spacing, layout and technique used for the "blind ruled" lines which the letters are written on).

I still like "page format" for the general layout of the page, never having seen "mise-en-page" in an English text before.

Of Helen's references, only one seems to applicable to mss. rather than printed books

http://tinyurl.com/yc4gjurj

and that one (which involves incunables, not mss.) seems to me to be somewhat somewhat ambiguous --though it does make a distinction between "textura" and "rotunda."

It definitely ain't my field.

Who's translating a text concerning mid-12th c. northern French sculpture?