Yes, but he had to get the information to write the book.
Just my opinion ^^
We don't know maybe Kish is just F...!@#!$%&...king with us.
IF YOU WANT TO KNOW WHERE I'M FROM TAKE A LOOK HERE MY FRIEND:Spoiler!
if nagato read jirya's book then that means he's probably perverted and so the sexy no jutsu could have worked on him
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.
What if everyone in the Naruworld saw Pein in a different appearance that could be possible but doubtful
what significance is it for those bodies to be specific to turn a shinobi into an avatar because pein can apparently turn anyone into an avatar and it seems the avatar is limited to one realm.
I do not think there is a specific reason to lookup anyone because it seems that the bodies are merely a conduit to the realm of pein. I cant remember whehter it was said that those shinobi used as bodies was strong. I can only remember jiraya recalling that he has met them.
Jiraya being widely traveled may just have met them as a passing moment or walked past them, met them in a brothel and not necessarily fought them. I think jiraya has met such a lot of shinobi both weak and strong.
To use only strong shinobi as avatars are stupid because it seem all the skills are lost and the focus of the avatar is on a specific jutsu type, unless it is explained that a specific afinity is necessary for a body to be realm specific and increase its potency.
unless the only reason is for pein to show off his powers by using strong shinobi as avatars and drive fear in the hearts of his enemies to show his strength, but this is questionable otherwise Hanzo should have been included as one of the bodies.
If only the strongest bodies are used then it hopefully will be explained that these ninja were more powerful than hanzo. Not questioning the fact of how hanzo was defeated by probably the same bodies, merely that any body can become powerful if used as an avatar, as presumed by the interrogation information received.