So I decided to have a go at guessing the coordinates of a proper 3rd vertex. It's some what complicated that there's actually an infinite number of answers since we only know 2 points, but if we treat the blob as a centroid which defines the plane of the triangle then it's possible to get fairly close to an answer if not the answer.
The coordinates for Skaudai and Blae vertices are: -5477.594, 504.156, 10436.25 and 8602.75, -219.813, 2641.938 respectively. The elevation of the center point on the Skaudai-Blae line is 142, the elevation (and they don't vary much in elevation) of a random selection of blob ruins is around -120 so the elevation decreased by about 260 from the middle of the Skaudai-Blae line to the centroid so the 3rd vertex would have an elevation of around -380 (-120 - 260).
Now it can be reduced to a more comfortable 2D problem, particularly since the delta in the elevation axis is so tiny compared to the other two. From there you get coordinates something like -5200, -5600, -380.
That's a bit too much fudging to generate a high confidence level target system but I'll leave you with this. If you enter the coordinates below into this online calculator:
That coordinate triplet creates an equilateral triangle that's accurate to a few 10s of arc seconds (1s of LY at these distances) and you arrive at Chi Persei Sector DQ-V C3-1 which is very close to the Soul Nebula, a bit down and to the south.
The two bookmarks in the bottom right are the center of the H&S nebular pair and that Chi Persei system.
That's not to imply there's anything interesting about that specific system but the Soul Nebula is very close to where a proper 3rd vertex would be in an equilateral triangle. If you treat the blob/bubble as a centroid you can create a triangle but it won't be equilateral. To my mind the combination of equilateral and obvious nebula wins over the blob being a proper centroid. For the triangle described by those coordinates the proper centroid is roughly where that Bleae Thua UQ-R book mark is.
There are in fact an infinite number of solutions by varying the elevation which is a perfectly reasonable thing to do in my opinion since -380 was derived by treating the blob as a centroid but it can't be if this is an equilateral triangle. Interestingly enough the higher in elevation you go (Soul nebula is around 120) the closer to the nebula you get pulled since you're sweeping an arc up and into the nebula.
And now I need a beer, my head hurts.