But, if you read the team roster of the team, and a player isn't mentioned on the roster, why would you assume that that player plays for that team? When we have multiple examples of various people in the mercenary guilds of Baldur's Gate, and have had several examples presented in other cities as well, and not a single time is a dragonborn even hinted at anywhere, it's not too much of a stretch to think that no, there really aren't any dragonborn there.
Your characters most certainly don't officially exist in Forgotten Realms. They have nothing to do with FR canon whatsoever. Why would you think that anyone outside of your table would think that they exist?
But, again, this gets back to the point of creating a setting that actually USES the PHB. It's not enough to just vaguely wave a hand at something existing and then telling everyone to just make stuff up. PHB options at a bare minimum should be given places in a WotC setting where those options exist.