In her comic and short story The Weakest Heart, you clearly see she can fight without the element of surprise (mainly in the story). In fact in the short story she won a fight against like 6 others, which was surely a theoretically unfair fight for her... but she won. Yeah, those were just a bunch thugs off the streets of Zaun, but still. could Fiora take on all six of those augmented guys at once and win? Just because Camille is an assassin, doesn't mean she can't fight with extreme prowess. And you keep thinking Camille is solely and assassin. She's not. Her lore says she's also a body guard, a spy, an interrogator. She's the sword and shield of her family. A multi tasked and multi skilled elite. And sure being adept doesn't compare to being a master, but Camille was adept at the beginning of her career. Surely she's become a master over 60 years.
And what does Olaf have over Camille? I'm really not familiar with his lore.
EDIT: I read Olaf's lore. Not entirely convinced he would defeat her unless she tried to fight like he does, by brute forcing his way strait into him. Camille is trickier than that. She dances around, dodges or blocks attacks and calculates how best to bring her opponent down with the maximum amount of precision. Likely she could kill Olaf before he even has a chance to take a swing at her. Fiora on the other hand would be a tougher opponent, but I still don't think she would win... at least not without Camille taking her down with her.