"Kronos" and "Qo'noS" are just different ways of transliterating the Klingon alphabet, that's all. Same way "Volodymyr Zelenskyy" and "Vladimir Zelensky" are two different ways of transliterating the name of the President of Ukraine (Володимир Зеленський), or the way the late dictator of Libya's name معمر محمد ابو منيار القذافي was transliterated into English multiple ways (Muammar Gaddafi, Qaddhafi, Qaddafi, etc.)
Why did we get a fancy alternate transliteration of Qo'noS's name when we didn't with other alien languages? Because Marc Okrand was hired to develop the Klingon language but no one did nearly so much work to make up the Vulcan, Romulan, Andorian, etc. languages.