Krakatoa has code that changes sourrounding tiles to coastal tiles and modify its yields. It should be separated from land with at least 1 tile of water.Krakatoa always spawns in ocean (close to island) but Bermudas always spawns close (next) to continent even on next tile to land. It wood be nice for Bermudas to spawn in ocean, may be no closer to land than 5-7 tiles.
Bermudas is meant to be an obstacle for ships (unique promotion), and that's why it spawns next to land and maybe between smaller islands, and that's not gonna be changed.