What japanese sets / eras have had the lowest print runs?
rtas
2
No rarity (base set), e series unlimited, L2-L3 unlimited (hgss), and most BW/XY unlimited.
Based on vibes.. there’s no official print numbers.
Welcome to the fourum! Nice to have you on board. 
Maybe you want to check:
Basically everything from e series through end of xy, with unlimited being hardest to find
And not to forget World Champions Pack and the partially wild backstory behind that.
Most underrated set in my opinion. 