Carlos didn't even know Umbrella was the reason for the Outbreak, yet we're supposed to believe that they sent them in there with enough information to be experts on a city they've never been to? The UBCS were basically expendable dogs for Umbrella, sent in on a suicide mission. Aside from higher ups, like Nicholai, none of these soldiers had any information and thought they were the GOOD guys. Again, RE3 goes out of its way to show how unprepared and uninformed the UBCS was. Which was good. It just solidified Umbrella's evil even more. If they change that for this, and treat the UBCS like more than expendable dogs, and have them there for an actual purpose, it changes the context of Umbrella as a company in a way that takes away from how cold and ruthless they are.
As for Carlos and his battle experience, again, his backstory made it very clear he was from a poor south American country. If we're to compare this to real life, those war torn areas are very poor, often using Guerilla warfare, and traditional scouting. There's no way South American war zones had computer tech savy intelligence agents in the late 80's/early 90's. Many of those countries now don't even have very great technological infrastructures here in 2020. So yeah, I'm finding it pretty hard to believe Carlos would be a tech expert. As for someone on his team? Sure, that's plausible, but again, one of the key parts of the UBCS story is that Umbrella sent them in with next to no information and woefully under-prepared, causing them to be wiped out pretty much just as easily as the police force was.