So I know this thread's almost a year old (dang) but I think I found the solution to your problem! This fork of AssetStudio should be what you need to properly rip the swizzled textures from the game's AssetBundles. It's been working for me so I hope it works for you!
https://github.com/nesrak1/AssetStudio/releases
https://github.com/nesrak1/AssetStudio/releases