I know that Tol Himring is already in the mod, however, it is not as Tolkien Gateway describes it. On the Tolkien Gateway page, it is described as a treeless peak after the First Age. Also, due to Maglor’s fortress being built on the hill and only the peak surviving, shouldn’t we see some ruins on the island and in the water surrounding the island?
I suggest that two new generated structures and one sub-biome should be added to the mod. The sub-biome would be called something like Drowned Himring. The generated structures would be called Himring Ruins and Drowned Himring Ruins. The Himring Ruins structure would spawn on the actual island itself while the Drowned Himring Ruins would spawn in the Drowned Himring sub-biome. The Himring Ruins on the island itself would be much more intact than the underwater variant.