Time for more character identity speculation. I'll just go ahead and put forth my best guess for every named character (and also badass train guy) instead of only the ones I'm pretty sure of, because it's more fun that way. The ones Elendra has confirmed for me will be stated as sure things, so if you don't want to know then obviously don't look.
Reyes - RPG101, confirmed by Elendra.
Daniel - Daniel is the major character that I just can't fucking decide on. Could be me, could be Dervish, could be a few others. I can't figure anything out based on his name, so I don't fucking know.
Calista - Smiral, confirmed by Elendra.
Pedro - I'm gonna guess Hank on this one. Douchebag villain guy, but soft spot for animals. Sounds like Hank to me.
Nacho - Zed, confirmed by Elendra.
Ceferino - I'm thinking Toellner, because he's El Presidente's enforcer guy and Toellner is often cast as important law enforcement figures in spamfics.
Demetrio - Could be the Jorick character. Stern and authoritative guy seems like a reasonable fit for me. However, could also be someone like Dervish for the same reason.
Irene - I'm guessing Nargle, simply because this is the Smiral's character's cousin and Nargle is the person that seems the best fit there. Also the brief personality mention of being feisty could fit Nargle. However, it could also be Idlehands, now that I think on it some more. Hrm.
Scarface white dude from train - Not enough to go on for a solid guess. He's a badass who works for the bad guys of the story, could be Hank if I'm wrong about the warden, could be someone like Darog if Elendra wanted to mix up the usual good/evil casting of various people from recent spamfics. That's the best I've got for this guy.
Eduardo - I dunno, not a ton to go on. Who's scrappy? Uhhh... I'll randomly guess Alphakoka because why not.
Felicia - I feel like this bitchy character might have been Sophi. She can be caustic at times, so it wouldn't be a big stretch.
Valentin - No idea. Could be anyone, but I haven't seen anything that even gives me a vague idea yet.
Jose - Eh, likely just a random character who wasn't actually based on a Spam person. Didn't have any personality to speak of.
Enrique - If I'm right about the warden being Hank, I think this is probably Vogel.