Would you mind posting a message to that effect (about the tests failing) on the SRFI 146 mailing list?
I did a little investigation, and it's because the (hamt) library is at srfi/hamt.sld, which means in Chibi it would have to be loaded as (srfi hamt). I tried to reposition it at the SRFI 146 root, but then (hamt-map) couldn't be loaded either. I'm sure this point is minor, but right now I don't have the energy to do whatever is necessary to make it right. Can either Marc or someone else look into this?