Ignoring the fact that the producers have out right said Shuri is smarter.... I feel like its comparing apples to oranges.
Stark, when Iron Man 1 came out was in a world comparable to our own (although there are flying helicarriers that can cloak themselves).
In a somewhat comparable world, he could make Iron Man armour, and arc reactor, a miniature arc reactor, advanced AI, that Barf system was civil war.
Shuri was born and brought up in an advanced civilisation with, what the more we learn about Vibranium, basically seems to be magic metal that can do anything, anyone wants it to do. How old is Shuri supposed to be? 20? Wakanda has been an advanced civilisation for hundreds of years it seems. Im guessing they needed cloaking technology as early as human beings could fly planes so, minimum a hundred years.
To me, Shuri, as smart as she is, seems to be standing on the shoulders of giants. Giants that had a magic metal.
Stark built a miniature arc reactor in a cave. With a box of scraps. Could Shuri do the same? Sure, probably.
But where they were brought up, with their respective levels of technologies kind of blurs the lines.
Having said all that, producers say Shuri....shrug.