I get what you're saying, but I think there is more to it than that. First, the emotional state of T'Challa based on all that has happened. He's probably a bit off his game, and understandably so. Walking through the wreckage of one's homeland would be far more distracting than walking through the wreckage of some other land that doesn't really have anything to do with you.
There is also the question of what tech he may have had access to. Yes, he's from one of the most technologically advanced nations on earth....but that nation lay in ruins. Who can say what they managed to scavenge or salvage? Who's to say how much of their salvage instead had to go toward the Illuminati's doings?
Then there is the plan itself. BP's plan to steal the bombs seemed like a desperation move, and the kind of thing they'd be ready for. And it's a bit unclear if they were expecting him or not.
On the other hand, Black Widow and Spider-Woman had as much time to plan as they wanted, very likely no limit on the resources for the job, no emotional connection to the location, and a clear objective to simply verify if Stark was a prisoner there, and then to possibly help him.
I don't see the two events as any kind of comment on BP's ability versus that of BW or SW. I think all three, and Shuri too.....although maybe not so much the White Tiger guys (sorry I forget their name at the moment)....are among the stealthier Marvel characters. I don't think anything we've seen contradicts that.