I don’t have the Pufferfish add-on so I can’t reproduce the same results that you have, So I am assuming the 27 curves in your crv object (the one just below Parting Line) came from the mesh object at top left.
I’m no expert on how the GH Loft function works, but I can say that the Loft generated from the 27 curves is really ugly. I culled out the first 6 curves (0 - 5) and the resulting Loft looks good. Adding just one more curve (Cull 0 - 4) results in the Loft getting bad at the top. And it just gets worse from there on up.
Typically this sort of thing happens when the Loft control curves are mis-aligned. In other words, when their starting/ending points do not have a nice smooth alignment. But that is not the case with your curves - their start/end points are nicely lined up. So there is something else going on.
Lofting curves 5 - 27 results in a “twisted” Loft, and I think this is due to the fact that curve 5 is the first one that includes what I call a fill-in web between the thumb and the hand. Curve 5 really should be 2 curves, one for the hand and one for the base of the thumb, which is separate.
But it’s not, and this continues for curves 4 - 0. I don’t know why your mesh tries to fill in the space between the thumb and the hand, but I’m guessing that has resulted in some weirdness with curves 5 - 0, and this in turn causes the Loft generated from them to look bad. My sense is you’ll have to fix this (somehow) before you’ll be able to get any proper results.
There’s an old saying in the aerospace industry : “If it looks good, it is good.” Your Loft doesn’t look good, but it needs to.