| Marcellano Durbin |
I would agree that Korva looks good. All four look good, in fact. Hryvnas would be a good foil, as you say. I can easily imagine connections either existing or forming between Marcellano and any of the ohters. Whether a second vigilante would cause issues is probably up to the GM. It could be amusing if the two vigilantes didn't realize that they both had secret identities for a while.
(Sudden inspiratin: a vigilante team in Irrisen who goes under the name "The League of Just Ice." Marcellano will write a comic opera about it.)
Whether or not Tandus' own story would get in the way would be up to you as GM. The story is one that fits with my understanding of the overall story. (I haven't actually read the adventure, so my understanding may be off.) It's up to you to determine how hard it would be to bring in Tandus' love interest as a captive in some group of captives somewhere.