Currently, version 2 of the Houdini Engine plugin does not support the Landscape Edit Layers that were added in UE4.25, but only the material/paint landscape layers.
Yet further down goes on to say
If an Landscape with edit layers is used as an HDA input, the landscape will import its (final) heightfield and paint layers as usual as well as import the heightfields of the individual edit layers using the layer names, prefixed by landscapelayer_.
So which is correct? I'm asking because using session sync I can see there is the landscapelayer_ appearing in there as part of the heightfield, (but they seem to be empty)