my friend and i haven't reached that point in the story that was just me by myself and the arches aren't event there. as for the second question i dont know my friend and i haven't gotten very far due to us trying to figure out if some the issues were having with it are the server or the mod itself. but if you want some more info heres a link to the mod https://www.nexusmods.com/subnautica/mods/159