To improve the mod compatibility this mod has with other modded biomes, I feel two tags should be utilized more. This is found in 1.21.1 NeoForge

First is this cold tag in the mod

https://github.com/barribob/bosses-of-mass-destruction/blob/master/src/main/resources/data/bosses_of_mass_destruction/tags/worldgen/biome/collections/cold.json

It should include c:is_snowy and c:is_icy biome tags for spawning in more modded biomes without needing manual explicit modded biome entries.

https://github.com/neoforged/NeoForge/blob/1.21.1/src/generated/resources/data/c/tags/worldgen/biome/is_snowy.json

https://github.com/neoforged/NeoForge/blob/1.21.1/src/generated/resources/data/c/tags/worldgen/biome/is_icy.json

Same for the end:

https://github.com/barribob/bosses-of-mass-destruction/blob/master/src/main/resources/data/bosses_of_mass_destruction/tags/worldgen/biome/collections/in_end.json

This can pull in the minecraft:is_end tag.

https://github.com/misode/mcmeta/blob/b7e7f5282f9cc2ca1bd01e9a4911beab4725cb4b/data/minecraft/tags/worldgen/biome/is_end.json

However, you would need to create and register a new class that extends RandomSpreadStructurePlacement and override isPlacementChunk to not spawn within 1000 blocks of world origin to prevent spawning on the Ender Dragon island. Definitely doable and worth it to get compat with all End Biomes

https://github.com/TelepathicGrunt/RepurposedStructures/blob/11e6b0bd15d0fe1d9a990a231511ecaf09ee35c7/common/src/main/resources/data/repurposed_structures/worldgen/structure_set/pyramids_end.json#L13

https://github.com/TelepathicGrunt/RepurposedStructures/blob/1.21-Arch/common/src/main/java/com/telepathicgrunt/repurposedstructures/world/structures/placements/AdvancedRandomSpread.java

Furthermore, you can have a custom structure class that check if the land at the spot is higher enough to allow spawning. This will let your mod avoid spawning in no-land modded end biomes

https://github.com/TelepathicGrunt/StructureTutorialMod/blob/211c5cdfb2e97a3a111df8aaba7697d409c38316/src/main/java/com/telepathicgrunt/structuretutorial/structures/SkyStructures.java#L103