Ideas
I am going to upload my save file but there are a few things I have noticed that seem important for you to know as it seems a multi-part problem. First thing is that when this problem happens with notebooks, romantic information and boundaries, it is usually from a sim somewhere in the vicinity of my sim and it comes from a sim that they are not having any interaction with and they do not know the sim or is only an acquaintance with them. I can't remember a time when a notebook or romantic notification came from a sim that my sim knew well.
Secondly, when a notification happens regarding how much a sim has earned on interest from having the Shrewd trait, it is always from a sim in one of my played households and I find that it seems to happen if there has been some interaction with them recently. Like running into them at a club, or having them over to hang out. Most of my households are friends and hang out or run into each other frequently but I will only get one notification in regards to the interest earnings of one sim as far as I can recollect. I can't recollect a time that there has been more than one so if it has happened, it is so rare that I don't remember it.