I had a problem finding software to test the integrity of filesystems when I created a FUSE mount for a decentralised filesystem a few years ago.
I'll face a similar problem soon, for the latest incarnation which will use rclone instead of FUSE, so it would indeed be interesting to run Bonnie against a range of rclone backends, including my p2p based fs. I'll let you know if I ever get that far.
Thanks for making this such an interesting read.