True, if it actually worked.I build the libraries anyway, so the +2is a nice free bonus.
I was about to open up a new thread (which would be my first one in about a year or so heh) on this issue.
The "+2

As far as I understand, it's a one-time bonus, and only grants +2


True, I always build a library in my cities, but quests call for prioritizing your building efforts and if I decide to run a quest (and do a mass library build in the relatively short time), I want my reward to be worth it

And on the subject of "+2

It wouldn't necessarily be a huge and unfair bonus.
If, for example, you have 10 cities, and have a library in each, you'd have 20 base

Let's say you have the basic science modifying structures in every city, which are the Library (well we assume you have these, thanks to the quest), Monastery and University. It'd be a total of %60 extra

Let's also say that you have 1 academy built by a great person, and 1 Oxford University.
Extra from basic

20 Base + 12 from basic buildings + 3 from special buildings = 35.
Yes, this bonus would add only 35 extra


So, it's not that great of a bonus, but it's nice anyway.