Can you die from spermatocele?

No. Spermatoceles are not a danger to health. Rarely they cause discomfort if they are large and they can then be removed.
No ... No, I have never heard or read about such concern in professional discussion or publication. Even in the worst scenario with very unlikely superimposed infection in a 15-cm spermatocele, a timely care will easily avert such an almost next-to-non disaster. So, I would not worry about it.