feast
筳 centers on a feast or banquet, likely involving bamboo utensils or settings.
筳 combines 竹 (bamboo) with 廷, which likely contributes the sound. The exact historical development is uncertain, but it may relate to bamboo items used in feasts.
Picture a grand feast where bamboo (竹) trays and utensils are laid out in a court-like setting (廷). The bamboo top and the court below come together to mean a feast.
For テイ, imagine a tea (ティー) party feast with bamboo cups: tea -> テイ, and the feast is served on bamboo trays.