First let's address the elephant in the room. This is a porn game.
Game Title: HengenSouki SHINE MIRAGE: countdown to defeat
Found fix, keeping question for future google searchers.
Figured it out while writing this question.
KiriKiri games cache the text in their saved games. Deleting the save shows the new translation. I can also fix it in the save file, but I wasn't very far into the game so no issues here.
Unrelated, I can change the save location to the game directory instead of under Appdata. Kind of cool.