To my unending delight, I've received a message yesterday evening... the travelling merchants have been found!

A friend hunted them down for me, with help of the search engine "ecosia": she found an image in the same style, searched for the name connected with it (Girart de Roussillon), landed on pinterest and found the image with a link to the manuscript there. Thank you so much!

It's Codex 2549 in the Austrian National Library, and it's available as a digital image. See it in all its glory here. According to the explanation, it shows Girart, his wife, and two companions, together with two pack animals. Seems it's not a merchant after all, that guy - he was a count, instead. The original person lived in the 9th century, but became star of a chanson de geste later in the Middle Ages - the Roman de Girart de Roussillon.

So... what do we learn from this?

A: Search engines are not all alike, nor are the methods of the people using them.
B: It never hurts to ask for help. I should do more of that.
C: Illuminations stand in context with the text, and it's really a smart idea to check that context. It does make a difference whether it's a travelling count or whether it's merchants... so I'd like to find out more about that. (Which means deciphering the text on the page, and deciphering the Old French, so probably nothing that will be done just now. But hooray, now I can!)