pretty sure it is gouma and not the author. Some of the extras are from twitter, which can and should be translated later.I mean they are just TL it, they have no fault in this.
The real culprit is the author Sal Jiang, something tells me at the time of writing this arc, the author was stalling for time to think of how to handle the confession.
That is unless these extras where published post-tankoubon.
Also, if you check the official english translation, they don't even have any extras. Just go straight from chapter 9 to 10.