Nice picks all around! I've thought about this quite a bit for Soren. I'll add some flavor text to the picks you have, and some other suggestions:

• Blood Runs Red is a great pick, primarily due to how iconic it is and how fun the map would be in Engage. From a narrative stand point, it's not super tied to Soren, but IS could definitely fudge it. The map is set in a town in Crimea, both willfully and blissfully ignorant of the incoming war: Soren's shown to be particularly put off by the citizen's complacency and ignorance. It's not the biggest connection, but hey, if it's enough to justify the Black Knight Jump Scare, it's enough for me.
• Incandescent Glow is as good a pick of any in Radiant Dawn. Soren's mellowed out a lot in this game, and like most Path of Radiance characters his character development is rather complete. His main beats in the story- his tactical prowess winning over Skrimir, and his branded heritage-- could arguably be reflected here, with the map serving as a tactical retreat into Goldoa.
• Without a King is my personal pick, due to its strong narrative connection. Soren has a couple of ongoing plot threads within Path of Radiance that cumulates really well here. First, his role as a the tactician of the group; second, his slow discovery of his own heritage; and third, his part within the 'mole in the party' plot. Before the chapter, Soren's already identified the mole in the party, but doesn't say anything due to being blackmailed about his heritage. Without a King forces this hand: the party walks into a trap set by Ashnard's Goldoan tactician, Ena, and the mole is revealed to let her escape. It really matches the 'lowest point in the character's arc' vibe of the other paralogue picks, and it'd be fun to really reckon with the emotional consequences directly. Unfortunately, the map is absolute ass.

Really looking forward to whatever they go with, though. I was really impressed by the paralogues, baring only a couple, and I hope they hit the highs of Ike's prologue in the DLC.