There are probably a few methods.
1) Just use the tool I used.
Unity Assets Bundle Extractor
You must be registered to see the links
Though if the installer doesn't work for you then you could just use the tool to patch the files directly. In the
original post I added the PNG files.
Extract that to a clean folder somewhere. Remember that folder location as it will be used in a bit.
Use 'AssetBundleExtractor.exe' to open 'TwinsGyakuRape_Data\resources.assets'
Select all Types with 'Texture2D'
In 'Plugins' it should now have an option for 'Batch Import'
Select the Folder that has the PNG files you extracted earlier.
Confirm the assets to import and click 'OK'
Click 'OK' again and 'Save Changes'
You can now close the Tool.
2) Just take this 'resources.assets' and 'resources.assets.resS' that I already patched using that tool and overwrite the original files (make a backup of the originals if you want).
3) Wait a couple days as NeZKyMaN has a translation in the works that is bigger and better then the Auto Google Translate.
Hope that helps.