She was wooden, but not a good Cary Grant way. She chose to come off as some stilted 20th century old money Translatlantic-warbling New England classist, but that isn't the character at all. She wasn't defined as an heiress. Her character is written as domineering with a new money, post-feminist outlook on everything. She wouldn't walk around doing this Lauren Bacall routine.
Nothing about her performance is convincing. This is a midwestern/northern woman who runs a billion dollar debt-collecting business that holds everyone with an entitled attitude in contempt, including conservatives, and that isn't just about an entitlement to money. Her contempt is for any sensibility of entitlement to anything unearned. She's particularly irritated by men who expect her to participate in notions of deference related to gender. To her, that is just another entitled attitude these men expect as a matter of cultural inheritance. She hates that. So why on earth would she adopt this veneer of a women who behaved in a way that was expected of them like she attended some finishing school?
This character, if treated realistically, is no nonsense, straightforward, and has no patience for the theatrical approach that JJL took to the character. She isn't afraid to adorn her wealth, but she isn't for pageantry. That's for airheaded beauty queens, and it's beneath her. Even a caricature of her character as a real person, which is what Fargo does, wouldn't have her to aloof. She would be more warm, more emotionally accessible, but willing to flip a switch on a dime, and put anyone in their place if they think they could leverag
e her inner humanity to contradict her will.
She was awful. Just awful.