Seeing and feeling Hayato's reaction, Ryuutaro could about imagine what would have to run through his head right now. While he still couldn't quite understand it, there was no reason not to be happy for him. Vongola or not Vongola, seeing Hayato glad was almost always a good thing.
Even if Ryuutaro had no idea what was up with these boxes. And for a moment he wondered why boxes should be any less weird than spinning tops

Ryuutaro smiled up at Hayato faintly. There was no 'congratulations' simply because Hayato should know by now just how natural Ryuutaro thought this was.