There's relatively little that needs changing about Breland, other than the racial percentages mix. I actually find it amusing that the Ruling Queen of Breland in the past was the primary cause of the start of the Last War, because she "virtuously" saw it as her duty to tell everyone else on the continent how they were supposed to live their life and was willing to kill them to make her point. How appropriate. Fantasy Karen.
Breland is a relatively cosmopolitan place, and the Brelish are accepting. Of course, like every other friendly and accepting and tolerant society, this means that they are often taken advantage of by others who are in their country yet only want a piece of that Brelish prosperity for themselves. They do not see cosmopolitanism as a viable end-state, only as a means to an end either for them personally, or so that they can eventually replace the naïve Brelish. As has been true in every society in every world, fictional or real, since the dawn of time, diversity + proximity = war. It's a low grade kind of war, and most Brelish are offended at anyone who has the temerity to point it out to them, because they stake too much of their identity in being nice and tolerant to admit that it's not really working, but they are gradually and slowly being dispossessed in their own lands by aggressive and entitled peoples from outside.
Now, I'm not exactly trying to remake Breland as a metaphor for America specifically and Western Civilization generally, but it's already set up that way, and even in the setting itself, it paints its metropolitan centers as famous for crime and corruption; usually carried out by non-Brelish if not even non-humans.
One notable part on this is that Breland, more than any other nation, has been relatively welcoming to Cyran refugees, so probably more of them are in Breland than in all of the other countries on the continent put together.
Breland population remixed:
Human: 78%
Hyperborean: 11%
Seraphim: 3%
Orcs and goblins: 2%
Shifters: 1%
Kemlings: 1%
Jann: 1%
Warforged: 1%
Other: 2%