You can’t trust the Landscape Coords node with a tiled world build, and honestly, it seems like it’s impossible to move the tiles around as a group, even with the tricks I found online. They always snap back to their old position.
I ended up figuring out the top/left and width/height of the landscape and storing them in a material collection parameter and a blueprint so they can align the landscape materials and be used for other things later.
I’m processing the landscape tiles into static mesh LODs again now (mostly to maintain an uninterrupted view distance as much as performance) and then I’m going to figure out how much stuff I can put down on the world, whether I need to set it up in streaming levels as well, and how well I can HLOD everything. Then I’ll get back into the main reason for doing this: developing a better procedural foliage system.
I also discovered another thing: make sure you set manual pagefiles and jack your virtual memory up to around 100gb. Even if you don’t end up using it, it’ll solve the main reason why you might crash when processing lots of landscape LODs at once.