Here's what I would have done with her:
Don't skip DIRECTLY to her making an iron man suit from scratch out of garbage. Give her a more realistic first step, like she figures out how to make her own arc reactor.
This is already a huge accomplishment, especially for someone her age. She gets swooped in on by a bunch of guys in suits, and it turns out that Tony set up a kind of trust fund/recruitment program looking for the next generation of supergeniuses. The goal is to make sure that they end up on the side of justice rather than supervilliany by giving them a productive outlet for their skills rather than them having to resort to crime to get what they need for their research.
Riri meets a couple of other people that have been scooped up as part of the same Stark Geniuses program, all of whom are smart as well, but Riri is the one to take a look at the program and realize that this is more than just a research lab, its a psychological evaluation.
Stark's program isn't to just find and provide for geniuses, though it does that too as a bonus. The REAL purpose of the program is to groom those geniuses to pick up where Iron Man left off, because some day Tony is going to die or retire and the problems he has been fighting can't be expected to just go away.
Give us an arc with Riri competing against the other geniuses and gaming the system that the others don't realize they are playing and she 'wins' and becomes the next Iron Man. Use the cast of other competitors here as an opportunity to establish supporting cast (helping her with science problems and helping her build her tech) as well as one of them who ends up going bad and forms a friend-turned-villain rogue.
This arc makes her seem like less of a mary sue, gives her challenges and the chance to prove herself, and immediately starts investing in supporting cast and villians for her that are unique to her, not just the sloppy seconds of the editorial department.