This isn't scientific or probative of anything but I have commented on the Dollar sign in the RN that looks like it had been changed from a Sterling sign. Well, I was just on the 'phone, holding the receiver with my right hand and doodling with my left on the message pad. Anyway, I am totally unidexterous (probably not a word, LOL) so my left hand doodlings were miserable specimens. However, I did notice that, when doodling 'sister', I had reversed both of the 's's in 'sister.' When I corrected them by writing 's' the correct way round, they looked just like the controversial dollar sign in the RN.
So, a highly subjective and completely anecdotal suggestion that the RN writer was in fact a right-hander writing with their left hand....
(Waits for Voynich to rip me apart :angel: )