arrive at, reach, intelligent
逹 centers on reaching a destination or a state: arriving at a place, attaining a goal, or achieving understanding. The 'intelligent' sense extends this idea to reaching a level of mental clarity.
逹 is a variant form of 達, which combines the movement radical ⻌ with a phonetic component that historically contributed the sound. The exact development of the inner 幸 shape is uncertain, but it likely represents a simplification or variant of the original phonetic element.
The movement radical ⻌ suggests traveling, and the inner 幸 looks like a person standing on a platform. Picture arriving at a station platform after a journey, finally reaching your destination.
For タツ, imagine reaching the top of a tall tatsu (竜, dragon) statue: tatsu -> タツ, and you arrive at its base after a long climb.