Normal changed to "Walk on the Beach"
Hard changed to "Boot" (i ran out of ideas)
Very hard changed to "A man of patience"
Overkill changed to "A man of action"
Mayhem changed to "Combat Op"
Deathwish changed to "Suicide Mission"
Death Sentence changed to FUBAR
One down option changed to "Do you feel like a hero yet?"
One down in-game is up for you to see.
Enjoy.
UPDATE 1: Changed the description of each difficulty to fit the mod more - shown in images
UPDATE 2: Changed the descriptions once again, this time for very hard and overkill since I had to make those up in under 12 seconds and they looked like a pathetic attempt to be edgy, so now they're taken directly from 2 specific loading screen tips from SO:TL.
UPDATE 3: Had to completely change the OD text in-game because it apparently was blocked by the damn "JOB OVERVIEW" text. Quite unfortunate, but it is what it is I guess.