This is a thing the idols do in the game, isn't it? You wave at them and they wave back or pose with you or whatever? If they didn't that'd be a waste of having prominent idols in a game to begin with. I had to look up the reasoning for why it is called "CALL13" day and, wow, that is quite a stretch just to give a holiday to the other (arguably better) Squid Sister. *checks notes* ...yep. "Squid Sister." I wasn't sure if that was just them or a general term for squid people.
Are the inkling feet really that much bigger than Callie's or are oversized shoes a style choice? Other than that silly question, there's no issues with this. Basic poses with your excellent facial expressions. Another new food from these games is shown here. Meatballs? Animal feed for that fish pet looking up at them? Some kind of gift that Callie gives the player?