Likely a variant of Cornell or Cornel, derived from the Roman family name Cornelius.
Corneall is likely related to Cornell or Cornel, forms that trace back to the Roman family name Cornelius. That lineage places it firmly within the broad classical tradition of Latin-derived names that traveled through Europe in many spelling forms. The result is a name that feels old enough to have historical gravity, even if this particular spelling is rare and specialized.
What gives Corneall its character is the way it stretches the familiar root into something slightly more ornate. The double-l spelling and final -all ending make it look more decorative and individualized, which can make a classical name feel less formal and more personal. Corneall has a quiet scholarly air, perhaps because it resembles names tied to learned or noble traditions.
It is uncommon, but its ancient Roman background keeps it from feeling invented. Instead it reads as a variant with a long shadow behind it.