Yeah, it got quite annoying that he didn't maintain any aging up because each new writer wanted him younger again. In order to get their ages, I look at the Power Pack. Alex was 12, Julie 10, Jack 8 and Katie 5. Franklin at the time was 4. The easiest age to look at now is Julie at 17. Meaning Jack is 15 and Katie 12. Alex should be 19, but now he's 24 (that seems too old). Franklin should be 11 (which I think he was before Secret Wars (he could also have been 10 since he lost a year when he was replaced by Psi-Lord). That puts him at 16. That is right since he's gotten his license.
Val is a bigger problem she should have been about 3 making her 8 now. But too many writers assumed she was older because of the genius level intelligence. She's clearly 11 or 12 now. My head cannon has her having aged up faster pre-Secret Wars time jump because of the odd circumstances around her birth.