The problems you run into are these:
You may have noticed already that the freewheel (ratchet mechanism) sits inside of the shown beltwheel.
The right crank and the bottom bracket axle are one piece, the freewheel (shells) and the bearings are simply screwed onto the axle, that is an old system called “Fauber”.
At the newer parts there is no chance to mount a freewheel inside of the beltwheel (you said pulley) and moreover that are standard bearings (inside of an excenter) in use. The axle is square taper and has no threads.
The only chance to repair that is for my meaning a 3D re-print of the old plastic parts - but, as far as I know, there are no printing files available yet (that may change in future).