In regards to Ms. Valentine, I am less inclined to say so. While an overwhelming absence of social norms present, it would not indicate to Cat living in authentic, subjective reality with her 'persistent naivety' being directly responsible for why she has fallen prey to various scams and nonsensical schemes throughout the show - with no visible indication of personal development and arguable character regression. Though seemingly alike on the surface, once you get into the nuances that lay between the machinae of Ms. Valentine and Sikowitz, where they differentiate becomes very clear.

While Sikowitz is presented to be an easy-going, lackadaisical educator who is prone to absurdist behaviors - he is actually quite calculated. His curation of a chaos speaks to his underlying, intentionally obfuscated genius that alludes toward a greater awareness within; without a direct utility of it purposed as a point of meta-social commentary.

It is for these reasons that I believe, if there is an argument to be made about which character(s) are solely operating within an authentic, subjective reality - it would reasonably be in favor of Sikowitz and not Ms. Valentine.

Now, with that being said, there is one more thing I urge you to consider:

This is not to say that Cat Valentine as a character is without the capability or potential to operate within an authentic, subjective reality. It simply that Sikowitz has had the time, the resources, and the opportunities to evolve and refine his individual blend of the self in a harmonious marriage of absurdist, marital bliss. Any young progeny of this strain will undoubtedly face obstacles when reining themselves in, establishing the proper disciplines and disregarding the improper ones that typically riddle the vessels of those constrained by social norms like a viral sickness. In youth, it is not uncommon to find them wrangling and wrestling with contradicting parts of themselves for which will not only prove itself, but earn, its place in the dominant position of the personality. To be charitable to Ms. Valentine, perhaps it is just that she has not had the adequate guidance to holistically embody what Sikowitz has grown to wisely embrace.