It's Wither2008 Touhou Style Difficulty Names V2 but I renamed to make it look like PD2 Difficulty Style.

Difficulty Name List:
Normal - Easy
Hard - Normal
Very hard - Hard
Overkill - Over Lunatic
Mayhem - Extra Mayhem
Dead Wish - Phantasm Wish
Dead Sentence - Overdrive Sentence

There is 2 version which the first version comes with a Skull (Which worked very well if you have Better Assault Indicator with Show difficulty name instead of skulls Enabled) and another version without a skull.

showcase:

BeardLib Are required for this mod and Install in Mods folder.