Excellent question. I did not address this in the paper, but I probably should have. The upper-bound you mentioned technically does not happen directly because of the nodes, but because of the increased "rate of events" (which can either happen because of the increase of nodes, or because already existing nodes suddenly create more events). Depending on m and k, there will be a rate of events that will cause things to mess up. I'm still brainstorming about this, but I believe we could fix this issue if we'd use a scalable counting bloom filter (https://haslab.uminho.pt/cbm/files/dbloom.pdf), instead of a normal counting bloom filter.