If it were strictly up to me, T'Challa would've told Shuri about the incursions, so that Wakanda could have its own scientists try to come up with a solution for the incursions or have contingencies if the worst case scenario was to come and an incursion was imminent. Most likely the Wakandans would've failed to find a solution and would have a life raft contingency, in which they evacuate as many Wakandans as possibly from Earth when the time comes. shyt goes down, they somehow all die except T'Challa, and T'Challa brings everyone back like in Secret Wars. The difference is the Wakandan people knew before dying that T'Challa had their back by providing them with key intel that saved a lot of lives. Much less animosity this time, unless a writer really forces it.
But regardless of the approach, T'Challa should've picked one and stuck to it. When you think about it, he sacrificed a shyt ton under the pretext that morality doesn't mean much if it doesn't help his people and his nation (annulling his marriage, straining his friendship with Cap in NA, losing the trust of his sister and his people, and so on). Yet he bailed out of the bomb plan because of morality in the end, resulting in him being disowned by his father and his ancestors. It's as if he couldn't figure out if he wanted to be T'Challa the superhero or T'Challa the King. He tried doing both and it blew up in his face.
If there's one "advantage" Shuri and T'Chaka have over T'Challa, its that they know exactly who they are from the jump and don't shy away from it. They are monarchs through and through have little to no interest in playing the superhero game. Shuri and T'Chaka would've used the bomb in NA, strictly out of duty. It doesn't mean that they would've enjoyed doing it. It also doesn't mean they are better BPs or better people than T'Challa overall because of that as well. All it means is that each BPs code, morality, and attachment to duty is different.