Where does “Κορνουάλη” come from?

Κορνουάλη (Greek) comes from English Cornwall, from Old English Cornwealas, from Old English Wēalas, from Old English wealh, from Old English īeġ, from Proto-West Germanic auwju, from Proto-Germanic awjō, from Proto-Germanic agwjō — water.

Ancestry of “Κορνουάλη”, step by step

StepLanguageWordMeaning
1EnglishCornwallThe country of the Cornish, currently having the status of a royal duchy in England belonging to the male heir apparent to the reigning monarch, and consisting at least of the Cornwall County and the Isles of Scilly
2Old EnglishCornwealasCornwall, inhabitants of Cornwall
3Old EnglishWēalasthe Welsh
4Old Englishwealhforeigner; Briton or Welshman; slave
5Old Englishīeġisland
6Proto-West Germanicauwjufloodplain; meadow; island
7Proto-Germanicawjōfloodplain; meadow; island
8Proto-Germanicagwjō
9Proto-Indo-Europeanh₂ékʷeh₂water
Every word from Proto-Indo-European h₂ékʷeh₂