Hey it looks realy nice!
Did you encounter the issue of visual seams at the adjactency edges?

I had this a while ago and in the meantime i found several solutions.

The old-school method is to use a vertikal mesh (so called skirt), and just live with the little steps that might occur.

Another way is to sample the heightmaps with a texture transform that basically overlaps pixels on the adjectency edges.

And you could use an algorithm for sampling the opposite edge of the neighbor and apply it to two of the current tiles edges.