I'm not certain if this is a bug, per se, but a bad description since there is a percentage factor at play. It might be 5 points at 100% of production devoted to research or 50% to devoted to research, for instance.
Personally, I think I might actually be glad that it isn't 5 flat per as there are times where I might not want to have very many (or any at all) research points. Say I'm delaying a Tech Victory (for REASONS) but I find I'm close to it during the End Game. Being able to turn off all research and just focus on other things appeals greatly. Sure, I could turn off a Tech Victory before the game starts (or even during it, if the option to do that remains when the game goes gold). But having the worry that others might hit the Tech Victory does add a certain panache to proceedings.