After a great deal of effort, I've finally downloaded all the community assets for the new, Py3 version (Alpha 2?). A couple of things....
Even though I copied over all the assets from the old version, I had to re-download dozens of them. This was probably because I had manually created directories for the old ones, and the new, automatically generated directories didn't match. Fair enough, but I ran into a couple of other problems. First, it takes forever to download everything because I have to do them one at a time: I can't just select a bunch of them (via checkboxes or multiple selection) and download them at once, and it literally took me weeks, because I did it while waiting on stuff in other windows (since I'm not gonna sit here for hours just downloading). For a person coming to Makehuman new, that's going to be extremely intimidating/frustrating/not worth the effort.
Second, I've also got dozens of materials that are being dropped into the master "data/materials" folder, rather than into the assets they belong to, and therefore not showing up unless I copy them manually to the right place. This is even though the materials in question are (in most cases, I think) properly registered in the database as belonging to the correct clothes. Not sure what's going on here.