Complex sentence: Dirk and Todd eventually finds a portal to Wendimoor in the Cardenas' house, and learns there that in the 1950s, the Cardenas had happened upon the boat that appeared in Bergsberg and found a child aboard it, whom they raised alongside Arnold.
Split into simpler sentences: Dirk and Todd eventually finds a portal to Wendimoor in the Cardenas' house. In the 1950s, the Cardenas had happened upon the boat that appeared in Bergsberg and found a child aboard it, whom they raised alongside Arnold.