Catherine of Aragon spelled her name variously during her lifetime, her daughter listed her name as Kateryn in her will.
https://en.wikipedia.org/wiki/Catherine_of_Aragon
"Spelling of her name Catherine of Aragon's arms while queen[104] Her baptismal name was "Catalina", but "Katherine" was soon the accepted form in England after her marriage to Arthur.[92] Catherine herself signed her name "Katherine", "Katherina", "Katharine" and sometimes "Katharina". In a letter to her, Arthur, her husband, addressed her as "Princess Katerine". Her daughter Queen Mary I called her "Quene Kateryn", in her will. Rarely were names, particularly first names, written in an exact manner during the sixteenth century and it is evident from Catherine's own letters that she endorsed different variations.[b] Loveknots built into his various palaces by her husband, Henry VIII, display the initials "H & K",[c] as do other items belonging to Henry and Catherine, including gold goblets, a gold salt cellar, basins of gold, and candlesticks. Her tomb in Peterborough Cathedral is marked "Katharine Queen of England"."
Yes, many Romance languages accepted C instead of K, but spelling of names weren't standardized until much later and that's true for many countries
I think many people dislike K in names due to unusual spellings and Kardashians, but it's entirely possible people who use unusual spelling are simply spelling names according to spelling conventions found in the home country if they are not English.