I see Charlene's problems/attitude as similar to Megan's in many ways. She started off with great intentions. She had enjoyed moderate success in her field of interest-swimming- which imbued her with confidence and might have caused her to underestimate what she was taking on.
But like Meghan, Charlene is not European. She does not want to try and fit in anymore. She clings to her identity as an African. She rejects certain expectations of her role as Consort...accompanying Albert to events overseas, mingling with other Royals.
Whether she does this out of shyness, lack of confidence due to her education deficit compared to the others i have no idea.
She does not understand Monaco. Her comment that she shaved her head to be "edgy" is a perfect case in point. Monaco is NOT edgy. It is glamorous but also traditional and conservative.
I am not prepared to say she is a failure. She is-most of the time anyway-beautifully turned out and elegant. She has provided two gorgeous heirs and is committed to motherhood. She has embraced the Catholic faith with apparent sincerity.
But...this is as good as it's going to get with her as far as "growing into her role". She has entered her 40's, and is has been in the Principality 15 years...ten of them as Princess of Monaco.