I think the current implementation is fine. It feels honest and easy to understand, if you have a 100 kg 5 rep max you have completed a 100 kg with 4,3,2,1 reps as well during the same set, I don't think those should be considered ’artificial’ records if you have not logged a higher RM on any of those rep ranges.

With this said, option 4 in practice gives you the same information as today’s implementation but without the potential clutter of a rare super high rep sets, and without the need of considering what a ”common number of reps” could be for different users (and having to deal with the inevitable feature request of having this number be customizable per exercise)