is this perhaps the same issue i ran into once? - http://polycount.com/discussion/172035/how-to-merge-uasset-files-into-projects i managed by creating my folder-structure behind unreal's back and reading the paths out of the binaries with a text-editor. as i recall the materials then magically found the textures.
it's just something i stumbled upon really. i would just try opening up those material uasset files in a text editor and there you'll find the texture paths. if you recreate that structure within your own project in explorer, populate it with the texture assets in the right folders and then load up your project in unreal…