I've never downloaded, looked at or read anything about AFK_Weye, but I'm rather surprised that a mod relating to Weye would be editing the south-east side of the Imperial Isle, since Weye is on the mainland west-central of the Imperial Isle.
Yeah, it's called Verres Manor, a part of a quest added by AFK_Wye. Which, although centred around Weye, involves quests all over the place. Adds this manner to the East of the Isle, south of the university.
I'm guessing that this land tear must have appeared after we removed some unintentional edits to the UL II ESP - in the previous version II must have covered the tear by accidentally editing land height to whichever cell you're looking at in the screenshot (you're in 11,8, but are you looking at the border to 10,8, 11,7, 11,9 or 12,8?)
Probably, I don't recall seeing it earlier, but then haven't been there much (haven't even done the involved quest yet.) But the tear goes directly under the house (along with another of similar size, entirely covered by the house.)
In the screenshot I was looking approx Nor-West, so probably more like 11,9. In fact, looking the the CS again, I think the tear is pretty much on the border between the two cells.