Unfortunately I do not think this snap fits within any of the existing known categories for classic confinement as outlined in Process for reviewing classic confinement snaps - as such whilst I understand it is not able to function fully without classic confinement at this stage, an exception is not able to be granted unless an additional category for classic confinement is able to be established that fasthistory would fit within - @pedronis can you comment on this?
Regarding man pages - I can imagine this may be possible to do within a strictly confined snap if the snap were to include the man binary within itself and use the system-files interface to get read access to /usr/share/man on the host.