Praise the Emperor!
The epic tracks from the Void Shadows and Lex Imperialis expansions were added to the Digital OST available in the Deluxe Pack!
If you already own the Deluxe Pack or any edition that includes it, your collection of music from the grim darkness of the far future will update automatically — no additional action required!
If you still don't have it, you may check it out here: View game page