In Curse Of Strahd, Cormac told Jarmo about Ghalwin's whereabouts, as well as the issues with his carpentry. He would later find Ghalwin's terse note, telling his parents he had joined his sister on her prophetic quest, and reported it to Ylyana the Starseer.
A reedy Druid-in-training born to Human Rangers of the Astralwood, Cormac was orphaned at a young age as his parents were killed by terrible monsters coming from the Sea of Trees. Naturally shy and unimposing, he displayed enough of a talent for magic that he was selected to become a junior Speaker of the Astralwood Enclave, and was highly devoted to understanding the roots of Druidic language.
He was tree-mates with Jarmo Maulgrave and Ghalwin Forrester, but often was not on the same schedule as the Keepers, and typically buried his head in books.