Thanks for translating!
I honestly saw Riolu's attack coming from a mile away. Though Lord Rosea may be a little miffed that his father was turned insane, I really don't think he's in any position to complain. Now that I think about it, since Lord Rosea didn't strike the deal before the protection magic made a beacon he contributed nothing and they have no reason to spare him. He may not deserve to die, but he certainly just sat back and watched while his father unfolded this plan. Lord Rosea only acted when he felt he was in the best bargaining position, and the children were kidnapped, not before. Hopefully he and Riolu will get punished for what they've done.
I sure hope the twins don't just run to the Imperial family after everything that's happened. The family is highly responsible for everything that happened, from locking them in the old palace to not acknowledging them as legitimate heirs and letting them be mistreated even after their mother was gone. They don't deserve forgiveness so easily, if ever.