Can you be more specific on how to replicate this one? I'm not able to myself. If you do I will be able to solve it.
Viewing post in Version 0.3 Bug Reports
I think these aren't the step to reproduce it. Followed till step 3 but no blank dialogue with Nezuko. Tried talking to Momoko in step 4 and no blank dialogues there either.
Wonder if there's something else. By the way ".,,,!" is not a blank dialogue.
Complete blank dialogues with English as language happens when game is not able to access every file in Streaming Assets.