As you already have insim, have you used it to select your non-aging teen and check him out. Using the 'age sims' cheat on teens (prior to FT) caused them to age up but not choose aspirations and not have romantic interactions (as they still had 'grow up' so were technically children). It'd be worth a check to make sure he aged properly and if not, put him in the aspiration reward and give him LTWs and all so the game sees him as a teen.
It sounds like an incomplete transition, like I had with fway's item unlockers hack (which he's pulled). My issue was on child-to-teen, but some teens then would only have child interaction options. I'd use a teleporter to get the adult on-lot, then make him selectable and age down and then up. Use Sim Blender, InSim (does it do that? I don't have it) or in-game cheat Sim Modder. Remake into townie, if need be.
For the cat, I've had similar and I think there was something wrong with the days left in age when I checked with SimPE. Changing that to something normal worked. The pet was aging, it just was aging from 1000 days left or somesuch so it wasn't changing the display. Sort of like Terrence Rowe...he has 500 days left in elderhood and no change happens at 6pm.