@Inlinebrother I asked @pfn on the RRF Discord server (https://discord.gg/uS97Qs7) if he was still using it. His reply:
I haven't updated it to latest and whatnot, it did kinda work before
I don't have a filament sensor in the toolhead, it's entirely driven by the ercf encoder
so because of the way filament monitors work on rrf, if you have a can-fd toolboard, you need to run the filament monitor from the ercf to the toolboard
Ian