Tomas Slancik

likely because you don't have UVs on the remeshed geo since displacement map relies on that

you may have some luck with Labs UV Transfer to transfer vertex uv attribute from original geo to remeshed geo

or alternatively you can create new UVs and bake the new displacement map

kta3d
...however, i have not found any way in Houdini to make a vdb that has anything other than a single 'density' attribute in a single channel. I would ideally like to channel-pack a VDB so multiple cloud/fog densities are stored into separate named channels/attributes (even if that doubles the file size)..

You can have multiple named float or vector vdb primitives in the geometry and when you save that geo into .vdb they all will be within the same single .vdb file

it does scale the timestep, some nodes do have Scale By Timestep checkbox

so on your Blur COP check Scale By Timestep (note that even on Timescale 1 this changes the blur strength as default timestep is 1/fps, so adjust accordingly)
then if you play with Timescale you should see the difference