It’s a bit strange that the new canon puts so much emphasis on the Kyber Crystals “bleeding”.
The name comes from the Kiber Crystal(s) in the 1975 second & third drafts of SW, which were magic Force talismans but not AFAIK used to power lightsabers.
Originally the name derived from the Khyber Pass on the border of Pakistan & Afghanistan: a far-flung frontier of the British Empire in the Victorian era, and hence featured in many tales of 19th-century imperialist derring-do. (The more things change…)
As a result, in Cockney rhyming slang “Khyber Pass,” or just “Khyber” for short, was used to refer to one’s buttocks.