Sea Weed only appears in Rough Ocean when creating a new world. But Sea Weed only appears in Swell Ocean when retrofitting an old world,
Hint: from my code reading, Sea Weed are intended to spawn only in Rough Ocean. Should "Barnacles_ReplaceSeastacks" function in "retrofitforestmap_anr.lua" use "seastack_spawner_rough" instead of "seastack_spawner_swell" ?
Retrofit an old world vs create a new one.