Not to be a nag, but isn't Yuuichi's birthday on July 31st? I'm unsure if the oversight was intentional--believe me, the newest Keisuke update isn't really a great time to celebrate it since he’s still figuring out how to not overwork himself, so I could totally understand a late birthday celebration during the break once everyone has the time, but since it's completely unmentioned (as far as I recall) I'm under the impression that it may have just been missed.
Although I think it’s a possibility that they won’t all hang out given the complexities of each characters’ life, but at the very least Keisuke would want to do something to mark the occasion.
I will say though that I imagine outside of the two main characters in the route, explicitly including all the birthdays in any one route would be rather repetitive since they’re all close together. The exceptions of course are Keisuke’s birthday which takes place before the routes diverge, and possibly Aki’s since he’s such a central character (but including Aki’s birthday might also make it feel like the others then have to be included as well).