i would be surprised to see damo again before a20 comes out, and nitro hasn't been updated since early a19.
nitro makes a much heavier world than vanilla rwg that some computers have trouble handling, this is 1/8th a part of why we stopped supporting it for ravenhearst. too many complaints about worlds in various ways that are outside of our ability to assist with. believe the bad Y locations is a side effect of nitro not being up to date with the alpha progression.
edit- think the latest compo version is also 47, so you might want to try getting up to date, could solve some things.
that's handled by the biomes.xml, not sure if that's what you were changing.