Ok so i tried to work with just the High resolution terrain on Sbustance and it's working. I don't know what i did wrong but when i use the Low res file and then i bake with the High res it's a mess in Houdini.
Did you use a Hipoly cage when baking in Substance? I'm pretty new to Houdini and Substance, but something similar happened to me a while back, and using a high poly as the cage solved my issue.
I don't know if you are talking about this: But i tried with just the High res file as the cage and it's not working either. Maybe i'm doing something wrong ^^