As with the other characters who are from Muru (Bantri, Arin, Curra, Galei, Oris, etc.), Cobb's dialect is based on 19th century western Irish, stolen from the book Irish Fairy Tales by Jeremiah Curtain.
Which is not to say these folks are intended to be Irish, but rather that I was looking for linguistic patterns that would feel a lot like someone was speaking a second language by stretching the new language over their native grammar. When Curtain was compiling the stories in his book, he focused on interviewing storytellers whose first language was Gaelic. I don't know how much he might have edited their narratives, but they're faithful enough transcriptions that the unique cadences of the various speakers show through, and in many cases there's that feel of shoehorning the grammatical conventions of one language into another. Just what I was looking for!
One aspect of Irish dialect I mostly had to drop was the "herself/himself" construction (example: "We'll have to move himself" instead of "we'll have to move him"). While it is delightfully distinctive, I didn't think it would scan well with the "xe/xer" pronouns used in the VotSS world. "We'll have to move xerself" would shift from linguistically distinctive to distractingly confusing to people who weren't familiar with how the gendered version of the pronoun gets used in Irish dialect.
I did try to keep it, though, for the second person pronoun, as per the "yourself" Cobb deploys here. I don't otherwise try to be too religious about making the dialect purely Irish; the people of Muru interact regularly with the people of the other provinces, who in turn have their own distinct dialects, and over time they start to blend together. Cobb comes from a group of people who have deliberately been living in isolation from the other provinces, so xer dialect is going to be stronger than most.