I can see this being non canon.

@Joshua  
The leaks from December 2017 mention a few things from an upcoming special that match this book.

@Background Pony #0115  
What makes you say that? Where’s the source that tells you that?

@neo4812  
We’ll see it soon.

Dude… This book just graduated from “want to buy” to “NEED to buy”!

@Joshua  
would’ve been nice if we saw that on screen

@Joshua  
not really a fan of it to be honest.

Yes, now they do it with the help of autotune.

So, the Dazzlings are reformed? Okay. That’s nice. ^^