After short research on Microsoft forums I have only bad news. Symbolic links are not supported anymore by OneDrive, junctions still seem to work but as I've observed on my example not really reliably. So had to search for alternative and I've figured out that I can do the junctions in the oposite direction. I mean that main folders are in the OneDrive folder (therefore synchronizing properly) and I've created junctions on the ServerFolders. And so far this works! So junctions seem to work well on DrivePool and standard windows features work well with those junctions as well. Including being WHS2011 server folders, sharing them on network etc. Waiting now for nightly backup to pick up the content.