Well she is going to stink out the film. I am not
just talking about 3 lines and acting is more than just talking. Is she worse than Olsen? As an actress maybe not, but for the selected role, yes. Like Mantis, Olsen fits because Scarlet Witch, like Mantis is supposed to be a bit odd.
Look at the body language in the interview linked above. Chris/Cap stoic / serious. Mark/Hulk off beat. Tony/Stark flamboyant. Clint/Jeremy pensive, quiet with an edge. Black Widow in control in command reading the situation. So chosen they were because their real life characters, auras, physiques and mannerisms etc fit their on-screen characters.
Bree's problem is that she is wooden, unathletic, lacks charisma, lacks charm and her acting is forced. Do you know why Chris Cap is retiring from the MCU? His reasoning sounds like a man "out of place" in Hollywood and that fits with the character of "out of place" Cap. Chris Thor is very sure of himself which fits with Thor. Mark Banner has this nervous energy with involuntary ticks, twitches, shuffles and comes over as if at some level he is unsure of himself which fits Banner etc.
Watch the Trailer where Thor summons Stormbreaker and she looks down at the hammer. In the later Trailer they have changed it so that she doesn't look down because she got her timing off. Watch when the movie comes out. The cut will not be the one with her looking at Strormbreaker because the Russo's watching that back will see it looks unnatural. Her job was to track the flight of a hammer she couldn't see and to start doing so just after her hair moved. It's a small point but added up hundreds of those sorts of things in a movie is what makes some actors more convincing than others.
Now I understand that not all people have the same degree of insight when it comes to reading people. That's why some people are year-on-year undefeated world poker champions and others think all "name race" people look alike. #Levels. Fair enough, if you think Bree acted well in what we have seen of her so far as CM then that is what you have seen.
I am fair and balanced like Faux News so let's see how she does in Endgame.
Let's see if she can eat them blows as convincingly as the Hulk did.