Huh, yes, I aged one Sim up now for testing and counted her days on the calendar, and yes, it's only 11 (I thought at first that the one missing day was only regarding the days until age up, but it seems to be the whole span).
And I looked into the old pre-patch tuning files and aging was done totally different back then (probably the source of the bugs). For example YA seemed to have got a random(?!, I don't think it ever appeared random though) number of days between 22 and 25 and then there was a multiplier for short and long lifespan. The multiplier does not work anymore since normal is now totally different than short and long regarding the proportions and it seems they just took the lower bound value as the new lifestage duration (22:2=11) instead of the upper bound.
I don't know. This is messing with existing games and there are many people that put months or years of effort into their saves. I'm happy that I'm only on gen 2 now otherwise I would even be more mad. I would be fine with cheating the ages of my main Sims since I know for sure what they were supposed to be, but I hate the idea that everyone else will still be messed up (especially the ones that just die).
And it's a no-go to introduce changes that make existing saves not compatible anymore and just being silent about it.
To be honest I'm not willing to put energy into the game at the moment with the current state.
And it's super sad because I was actually excited about HSY and it would have been the first pack that I had bought shortly after release. But I won't do this now, especially since I'm suspecting now that high school on short lifespan will be even worse than on normal.
Sorry for the rant, my negativity is not directed to you @crinrict but to EA. I really appreciate your help!