Falcon Heavy managed 27 rocket engines just fine, so the N1 problems has been solved. In fact I don’t think multiple rocket engines ever was a problem with the

Falcon Heavy managed 27 rocket engines just fine, so the N1 problems has been solved. In fact I don’t think multiple rocket engines ever was a problem with the N1. Its problems were quite different. SpaceX is able to shut down failing engines quickly, as has been demonstrated so multiple engines don’t present added risk. Vibrations from multiple engines is something they are able to model much easier with computer simulations today.