As a Deaf person (and sensitivity reader for Deaf characters) I have a strong love hate relationship with this series. Much of it is accurate. 
There are many parts that are frustrating from a Deaf perspective. A few examples. People just speak around shoko and only sign when she’s needing to know the conversation. 
Or, a very prominent part towards the end of book 3 when shoko starts to speak. I clearly understand what the purpose is. But it feel incredibly disrespectful to turn her Deaf accent into a slew of similar sounding words for affect. “I lub moo” okay… 
Not to mention her asking shoya “I sound weird?” And him saying “yeah.” Again I know his character and his development. But. It wasn’t cute. I’ve said it once. And I’ll say it again million more times. It is not romantic to force a Deaf person to speak for you. (And then to say they sound weird.)