Poor try. The fact that her feast day was restored an an optional memorial does nothing to "reaffirm" the validity of her existence.
Fiction is fiction, is fiction.
Pray to her if you wish. Praying to a fictional charachter is no less useful than praying to any authentic dead person.
There is as little historical evidence to disprove her existence as there is to prove it. The same applies to Jesus. It is faith that leads us to believe.
That a Catherine of Alexandria was martyred in the 3rd century is not in question. Hagiographers have simply claimed that they were unable to attest to much of the legend that surrounds her. There is still much to venerate.