Yeah! It’s sooooooo stupid! I choose the Jamaican voice for my second character and I got stuck with the same, boring voice my first character had. This game does soo many things to make me rage.
I need to just uninstall this game and enjoy good games like The Witcher 2. At least for the sake of my blood pressure, lol.
I thought something sounded off and turns out my character’s got their voices switched too.
I really hope they provide some way of fixing it short of delete and recreate.
I’ve been having exactly the same problem. Like a lot of you guys, I’m a big RPG-er too, so having my character’s every detail match how I want it is quite important, as I’m sure you can appreciate.
I think the game is getting confused about which voice is assigned to which character, since for my very first character, I chose the fairly generic American-sounding voice. Since then, every other character I have created (and that’s a fair few) has had this same American accent, regardless of which voice I chose.
I’ve tried using the glitch that so many websites talk about to try to change each character’s voices, but alas, it hadn’t worked for me yet. Here’s hoping that a patch will be released to clear this up and give our characters their original voices back, save for deleting and starting again. 
Chose the Irish voice too (on 360) and am getting the same ‘mucho bad guys’ response to sighting enemies. Thought perhaps it was another player (or rather bot) in game.
Aware that I’ve just posted, but it occurred to me that a similar bug happens for me. I initially sided with the Resistance, but sometimes when playing Security, the player model isn’t the one I created. Might be related to the voice bug.
My second character also got his voice changed -_-
It was changed from David Yip to the american voice.