It does seem a bit strange, you're right. When you read into it though, this city seemed to have a higher cobbler population than most, as alluded to by the author.
> They were organized in different guilds, based on the street in which they kept their shops. In 1360, nine cobblers’ guilds were attested in documents, all situated within the city’s walls
I know almost nothing about medieval France, but perhaps peasants from smaller surrounding cities may have come to this one to learn or work, leading to this skew?
There's always an overlap of skills. Cobblers may have been tailoring on the side but wouldn't be counted as such. I've been to many dry cleaners that will do alterations or repairs on clothes but also will do some light shoe repair as well. They won't make you a shoe but can fix a broken heel just like I'm sure there are cobblers out there who are capable of clothing repairs.
> They were organized in different guilds, based on the street in which they kept their shops. In 1360, nine cobblers’ guilds were attested in documents, all situated within the city’s walls
I know almost nothing about medieval France, but perhaps peasants from smaller surrounding cities may have come to this one to learn or work, leading to this skew?