Yeah, there's a bunch of things that are quite overwhelming. The biggest issue to me is the factor that the speed of time in game makes it difficult to truly enjoy these things if I participated, and with the fact some happen simultaneously, it's too much. If it was with my modded game, no problem. But even so, the vanilla version needs work. My only respite is the fact that it if is ongoing, my sim doesn't need to participate. It can be cancelled early. Though there are some events my sim just doesn't get invited or prompted to go, so I only get a notification, which is fine. YMMV.
As far as the calendar is concerned, I haven't really bothered to check, but it might be edited out? I know one can add events. Upfront, I'd think if we don't have that, there should be an ability to do so. In fact, overall, I'd think a checklist for the sim I'm playing should be available to opt in/out of things in game. That would at least mitigate the constant load of things to do. I can only deal with so much so far even with some cheats, but there are certainly things that happen out of my control and it's the constant need to manually deal with that being a pain. This is 100% not an issue if I modded my game. There honestly should be better control like that because otherwise, playing this game is a lot less like a sim and more like playing some hard mode at life. I'm supposed to chill, not get so much anxiety.