I wouldn't say she's incompetent. She's a smug bitch, that's for sure, and she gives me serious sus vibes- the initial meeting with her was downright creepy and borderline villainous, but the system thus far, and since the initial guardian decree has been running *as she intends*. I'm not saying it's perfect, or even right, but that it's running how she wants it, and that disqualifies her from incompetency.
I also doubt Croixelle is gonna openly revolt against her, at least at this point in the story.
I don't say the above because I'm a fan of the queen- I'm not, the psycho bitch was fully prepared to ice you during your first meeting, and nearly did if you dare state you think it's a *teeny* bit fucked up that Kendra can just go around killing people and her response amounts to "skill issue". It's also pretty telling that her husband chose to die a natural death, when he could have likely been kept alive indefinitely with the magic at her disposal. Makes me wonder if he really didn't enjoy his life with her, and instead used the position to help as many people as he could, where the queen would not.