Alright, I'll try writing that. It's been some time since I've written something for the world generation.
After seeing a few pictures of the End island, I have to completely change the algorithm. It seems that the island is not related to a sphere in any way; instead, it is made of two modified random heightmaps, the top one with low frequencies and the bottom one with higher, and an additional offset to height based on the distance from the center. The end stone is then placed in between those heightmaps. A distortion is added to the lower heightmap, so that there are small crevices.
It is even possible that instead of the lower heightmap, a 3D noise is used, but definitely the top surface is made by a heightmap.
After seeing a few pictures of the End island, I have to completely change the algorithm. It seems that the island is not related to a sphere in any way; instead, it is made of two modified random heightmaps, the top one with low frequencies and the bottom one with higher, and an additional offset to height based on the distance from the center. The end stone is then placed in between those heightmaps. A distortion is added to the lower heightmap, so that there are small crevices.
It is even possible that instead of the lower heightmap, a 3D noise is used, but definitely the top surface is made by a heightmap.