Rn if I use a datapack like towns & towers their villages won't generate because the biomes are for example "modernbeta:beta_forest"

I think it's be better if instead of doing that you used vanilla biome ID's (I'm not talking about what Beta Vanilla is. No modern biomes generating, just reusing their ID's) so for example minecraft:forest and simply modified the foliage color with an integrated datapack of your own.