Except that classical Latin pronounces the C as a K. English started mispronouncing it as an S eventually, after the black plague took out much of the aristocracy in England, and the commoners who rose to fill the gaps began to try and pronounce things with a “french sounding” accent, to try and belie their commoner origins, and to sound less Germanic/primitive (which is also why the dropped the K sound from Knight, Knife, Knee, etc). Also contributing to their mispronunciation of Cerebus was an illiteracy of Latin and Greek.
But I still dont think that is right. It’s like 200 years from now, if “Axe me a question” is deemed “acceptable” because of common usage.
(This is only applicable if you are intending to name it after the legendary creature. If it is named after some other cerberus, then I guess it should be pronounecable any way you want, lol.)