It wouldn't have been Buffon who visited Abyssinia. The author of the species is either (Daudin, 1802) or (Daudin, 1799) depending on where you look. In either case the publication in question appears to be one of Buffon's multi-volume "Histoire Naturelle" works, and presumably for Daudin to come into the picture, Buffon must have credited him for the discovery of the species.
I don't think Buffon ever visited Abyssinia, but a scenario involving Daudin is just not possible, I'm afraid... Buffon died in 1788, when Daudin (born 1776) was still a kid.
One problem with Buffon's works is that they have been printed again and again, so it can be hard to find the original version. The oldest version of the description of the
baglafecht I can find (1775) is
this one.
He did not credit anybody for this particular bird. However, if you scan Buffon's works for descriptions of Abyssinian birds, you'll see that for most of them the information is credited to "
M. le chevalier Bruce". The
baglafecht appears somewhat as an exception for this, but the directly subsequent species,
"le gros-bec d'Abyssinie" (the Abyssinian grosbeak; this is the village weaver), shows the usual credit: "
Cette eſpèce eſt nouvelle, & nous devons tout ce que nous en avons dit à" (This species in new, and we owe all we said about it to) "
M. le chevalier Bruce." This refers to
James Bruce, a Scottish traveller whom Buffon met in France in 1773.
(This, I think, makes
James Jobling's earlier suggestion that "
baglafecht" might have something to do with the "(yellow) Bagla finch", a bird that Bruce had seen and drawn during his travels (see eg.
here), far from unlikely...)
Edit: No, OK, I understand: what Daudin did, is to make the name available nomenclaturally (as
Loxia baglafecht Daudin, 1802). Buffon was not binominal and used only French names, which are unavailable, thus a scientific name will never be credited to him. Daudin did this apparently in an index that was added to one of the re-editions of Buffon's complete work. I've been trying to locate the correct volume of the correct re-edition, but so far I've failed too.