After the mission on Sauria, when Fox, Krystal, and Tricky are sharing a moment together, how did Tricky know about Fox's romantic feelings for Krystal? Think back to Star Fox Adventures and that awkward moment the first time Fox traveled to Krazoa Palace. Even though Tricky couldn't warp with Fox, he could still communicate with Fox.
Tricky: I can still hear you!
So Tricky could apparently hear everything Fox said, and that moment where Fox first saw Krystal and immediately fell in love yep, he heard that too.
During the same Sauria cutscene, pay attention to Tricky's behavior. Even though he's grown a lot, it's clear he's not fully mature yetindeed, it's only been a year since he was knee-high to Fox. Fox has to tell Tricky that he's leaving him in charge of Sauria, and judging by Tricky's reaction to that it's clear that he has never been in charge. Putting all of that together, that likely means that the King and Queen EarthWalker lost their lives during the Aparoid invasion.