So, I bought the game and also downloaded your version of the game (because you separate the data files and I can access them easier), and I noticed that in my full game, 井伊直正 (Ii Naomasa) and 真田幸村 (Sanada Yukimura) have their opening, ending, event, and ero-scene voice lines, but your translated version only includes their ero-scene background loops and system lines. In short, you're missing voice lines from the DLC 3 characters. Looking at the updates for DLC 3, you're missing the last update that finished adding the rest of their voice lines in. DLC4 specifies that you don't need DLCs 1-3 purchased/fully updated to get it, so you probably missed the final DLC 3 updates.
Would you be fine with updating your version of the game and adding them in? If not, I can try to figure out how to extract them from my own Japanese game.