No, unfortunately, I didn’t find a solution, at least not inside the UE. I had to give up on my project.
I wanted to create a Hexaphere-gameworld, then let the player set up the parameters for its overall look. Next step was to use 3D perlin noise to create Hex-tiles with landscapes that fit seamlessly together. I already had added a LOD system too. All of that worked well but the performance.
Since all the tiles were the same and only defined their shape by the same global material, I found it quite logic, to instance the tiles. Maybe on a loading screen or something. But I never got it to work.