as far as I got.
I am in this mess. Le me tell you how I handled it, sort of, but its no solution. I had a corrupt drive and a back up and I restored to my new HDD from Time Capsule and a restore from a Vault. Just like you lot.
Now when I load Aperture it has no thumnnail, only about 30 I'd say, which i'd say out of 50k is not much. Luckily I had read about recovery software from DiskWarrior of which can recover data - luckily for me it did and I got pretty much my whole drive back, the old broken one, but it was physically damaged still. But then I remembered reading that it lets you run programs from the bad HDD, so I ran Aperture.
Aperture, for one time only so take a screen shot, flashed up all the unsaved images yet to be in my vault, then preceeded to connect to my newly formed Library on my new computer, but linking to the images on my bad HDD - the result was that all 50k of the images thumnails were being generated, on a 5400rpm HDD and over USB 2 this took about 8hrs. I woke to an almost complete library.
I then took the method of exploring inside the library to see projects tht had not been saved and comparred file sizes, all of the pictures that were not in Aperture were in the Photo folder, sort by date os a good method and I had about 200 not saved - which most were shot on a camera in a single day.
I then tried copying and pasting the projects to the new library and seeing if it would repopulate with the pictures not saved, it didn't but did create a new project with an affixed "(1)" - you have to open the library when Aperture is closed, c&p from the old library (from your corrupt hdd) and then open Aperture. Like I said the images are not put back in, the ones not saved in your last backup of Aaperture and I haven't trued importing the right ones which would can tell from the Photo folder sturcture, but that could work as Aperture could match up the file to the metdata present in the project you copied in, maybe.
But then I did a show image in finder and all of the images in my copy of apeture, no matter if accessing Apeture form the new HDD or the old broken HDD linked all images to the old HDD! oh no!
This is too confusing, so I'm going to recover from TimeCapsule as I did a fresh OS X install then from TimeCapsule because the HDD wouldn't show up - you might have un into this problem. But I intend to restore from TC as I don't have access to my TC backups otherwise.
Then using DiskWorrior I will restore the Aperture stuff and hope it all works. Oh and guess what the library I had was from before the point releases, so if you access the Library (mine was from 2008) its actually got to be updated to work with the current (2.1.4 ~or something) release, then I stumbled upon another library, which cannot be diectly linked to (where I found those missing projects) in a folder called "ap2", which is adding more confusion.
Good luck, but I'm reinstalling (at great time cost) from TC, not a fresh OS install, then recovering my HDD from Disk Worrior.
Now I've scoured the web but nobody has gotten more info than that on this issue. I didn't backup the Library because just a single kb change from metadata or even closing down Aperture not even using it can change the file size and its a multi GB file so even Apple recommends excluding it from TC but I think I'll have to maybe make a copy. Apple needs to release Aperture 3 with TC compatibility BIG TIME!