Long triangles have nothing to do with the problem here .. see you have longer triangles and they end up perfectly fine.
If anything, it might be the clusters (high distribution of edges ending in one vert)
You can play around with the edges, rebake and see if it fixes it.
For example in the image below, I just spin the edge to take the tension out of the verts.
But to be honest there's something dodgy here ... it might be anything from the baking cage to improper use of smoothing groups ... that's one of the reasons I use xnormal instead of max these days for baking.
I suggest using high specularity material to test for smoothing errors.
Also be prepared results are rarely 100% perfect, but might be good enough to work around them. (once you have a diffuse/specular textures, it usually hides minor issues)