With CRZ screwed up at the moment I am not sure if this will work, but it should still work:
Take a toon, any toon, but one that can fly so it goes faster, and park it in Dalaran. This should be a toon you are not doing anything with, so you don't have to keep moving it to and from Dalaran. A Druid would work best, as you have instant cast flight. Next, get some battletag friends on different servers. Alternately, get one friend and have your toon be a level 1. This will go slower movement-wise, but you make up for it in the next step. The key to this is being able to group with someone cross realm, and you getting your character 'pulled' to their realm. The reason using a level one works well, is it allows you to be grouped with another level one, and you get pulled to their realm. If you have a lot of battletag friends on different realms, the level does not matter, so long as they are equal or above the level of your character. Now, once you have your character camping in Dalaran, and you have your battletag friends ready and willing to group with you, start grouping and checking locations for the books. Nothing on realm X, thank them for their time, leave group and get grouped with someone on another realm. If CRZ is working, try to pick people to group with who are not on the same connected realms, or battle groups, as you will in effect be looking at the same spots, instead of the spots on different servers. This one hundred percent worked for me, and I was done with about 6 hours of total time, only looking every so often each day. How this works is you look in the several spots the books spawn to see if one is there. So you start on your server, look in the 8 spots, find nothing, get your friend to invite you to a group. THEY have to invite, otherwise it won't work. Then look in the 8 spots on their server, and keep doing this, hopping servers. Don't ever camp a spot, waiting for something to spawn, look elsewhere. Doing this you should find at least 1 book in no time, literally. Obviously, most of the time there won't be a book, half the time there IS a book, it won't be one fir the achievement, and 8 times, the book you need will be there. Once you get a book from one of the locations, stop looking in that spot, you got the book, you are done. Eventually, you will have just 2, and then just 1 left to find, and by this point you can either camp the one spot on your server, or go all out, and spam group with people to hit as many servers as possible. So, when I did it CRZ was working, so instead of having a possible 200 US servers to hop to, I only had as many battle groups or CRZ'ed groups to bounce between. With CRZ being messed up, you might just have to make sure that you don't search on two realms that effectively share the same Dalaran server.
TL;DR: group with friends from different realms, and look in their spots for the books. It works, (or it worked a few months ago when I did it) this greatly increases the possible spawn points for the books, and greatly speeds up the time per book found process. From weeks or months to days, hours if you spam group and hop as many servers as you can. A book is bound to be up on some server somewhere, and looking at all of them instead of just your own is the fastest way to find it.
Absolutely open a non-achievement book to force it to despawn, or the next time you look there, on that server, that same book might still be there. They are there until someone opens them, then they despawn after a few minutes.
Also, what I did exactly was make a ton of level 1 orcs on different realms. When I thought of this, I already had a character with a few books found already. I have 2 accounts, so I took my Mage on the second account that was at least level 80 to have access to creating the Dalaran portal. Then I parked that Mage in the Valley of Trials and grouped all those level 1 orcs to bring them to the mage's realm. Then I created the portal to Dalaran, and poof, level 1 orc in Dalaran. Next I left the group, and I was phased back to the character's home realm. Next, I moved each orc to the different spawn point for the books. If a book that I needed was up, I DID NOT open the book, but took the character that had some books found and got it grouped to that realm to open the book, thus adding to that character's achievement.
A key note here, the pet is account wide and unique, meaning you can only have one. The achievement once complete gives you access to the pet on all characters, everybody knows this. But you may not know that progress on the achievement is character specific. If you find book 3on one character, and book 5 on a different character, each has found only one book, not two. So you must open a book once you find it, by the character that has the most progress.
If there are people here that all still need this achievement/pet, I would make a 'super group' and search your realms together. Once someone finds a book, group your friends to the server the book is spawned on, and loot it together. If you jump the gun, and open the book before you get everyone there, it might despawn and you will have to find another server/wait for the respawn.