Wow, you translated them pretty well I'd say! I'm impressed! :D Except for the manga one--just a bit off! But you're close, I think!
And as for the grave...hehe. Maybe it's a bit intentional! ;-) I do intend for some of these characters to reappear in future projects, though! So maybe the puzzle will begin to reveal itself more and more as that happens.
I feel so flattered you enjoyed the game enough to want to decipher the codes! Thank you so much for playing, I hope you'll stick around for future projects too!<3