For the Unreal translation, go here. Be aware that some files are shared between translations, most of the time without any difference between them. Files with a shared filename which need a separate translation are placed in separate sections in the same file. (See Engine.int for an example.)
These files are shared between Unreal/RTNP/Unreal Gold and Unreal Tournament.
Other important files
GOTY/Bonus Packs 1-3 Edition additions
Bonus Pack 4
Rocket Arena: UT
Content related to the GOTY and v1.60 versions.