Hello Nick,
based on the test-startup script of recent
PRS650.Flash.Package.1.05j.zip it should be possible to reload dutch language assets.
First install version 1.05j.
Then, according to borodas FAQ, place the folder test-startup (see attached rar-archive) in the root of IM. The folder contains a modified "startup.sh" script, and a sub-folder nl. There I placed the original dutch asset.xml and the english about.xml - needed to configure the hacks.
Restart the reader w/o connection to USB.
If all works out the russified laguage-asset will again be replaced by the dutch one.
If something didn't work. Restart reader attached to USB and remove/rename the test-startup folder in IM.
Please note, that you are doing this at your own risk.