What I am thinking about right now is to have different random event lists for each life stage (each would have a combo of positive and negative events), and then an age-sorted list of playables. Then have the randomizer roll events for each life stage, such as 1 child, 1 teen, 1 YA, 2 adult, and 1 elder. As sims age up, their names get shuffled to the next life stage in the text file and then removed when they die. I don't have your strict method of playing 2-day rounds, so I maybe I'll just roll it once/season.
I do something very similar except I only have negative events. I figure that I sufficiently keep my Sims happy; so, they really don't need any random positive events excluding the game given ones already.
My negative events are pretty life-altering and include death, adulterous spouse, loss of a job, death of a child and death of a close family member. I use each type of death as a separate event for the chosen Sim, but death of a child and death of a family member are each only considered 1 event (I determine which child/family member and how they die randomly afterwards). So, it is likely that the chosen Sim will die somehow. For YA, I add fail a semester of school to the events.
After the random event, I go a step further and roll a dice to see if the Sim will triumph over their negative event or go into a depression. If they triumph, I may change their aspiration (re-evaluate their life goals based on the event), give them a genie lamp or fulfill their wants for a Sim week as best I can regardless of my plan. If they slip into a depression, I fulfill their fears as best I can regardless of my plan for a Sim week. While depressed, they will also provoke other Sims to fight. If the random event was an adulterous spouse, I roll the dice to determine if they will divorce or not.
I use almost the same frequency of events as you except for elders. Half of my elders are randomly chosen for accidental death simply because in reality the accidental death rate for elders is quite high compared to the other age groups (typically 3-10 times higher). If I have a small YA group, I may exclude the death to that Sim options.
I always group my Sims based on when they were born into a generation (well, kind of a generation for lack of a better word). Each generation ages together. So, after aging each group appropriately, I determine the random events and they must be fulfilled before the generation ages.
It's funny, I spent some time working on this and then never did anything with it.
Here, I'll attach a simple Excel file that I put together to organize random events by lifestage. Many of the scenarios were pulled from Jade's, but I think the yellow highlighted ones are ones I thought up on my own, or ideas from others in this thread.
Should be pretty self-explanatory. The idea was to sort by audience (each lifestage and household), and then input it into a text file to use with Hook's Randomizer. I just never got around to it. Maybe someone else interested in this concept will find it useful?