I agree, but in a typical combustion engine there is also a comparable amount of stress on connecting rod bearings and the typical design of a crankshaft also p

I agree, but in a typical combustion engine there is also a comparable amount of stress on connecting rod bearings and the typical design of a crankshaft also puts a lot of side-force on the entire piston and rod assembly. I can't find enough information on their "reciprocator" to see how it differs from other swash/wobble-plate based axial engine designs.