The whole "brand America" doesn't sell overseas stuff is hokum... or overblown at the very least. The world has been on a steady diet of pro-American movies and TV shows for decades now.
Other than a loony minority, who either way wouldn't have had any
say with respect to the box office bottom line, I don't think anyone sees "America" as the bad guy. Do many people over the world disagree with some of the politics and methods used by the government and large corporation? Absolutely. However, newsflash... so do many Americans.
"American ideals" per se, especially the ones Cap embodies, people all over the world are on board with, almost universally.
Let's take a look at the WW grosses of the Phase 1 movies as a %age of total gross.
Yes, this is something of a simplistic assessment that doesn't take into consideration many
factors like how recognizable a character was in the US vs. outside the US prior to the movies, the ascendant WW popularity/buzz surrounding the Marvel Studios movies, etc.
However, if I were to surmise, the "America" part of "Captain America" didn't really affect the WW box office take, and even if it did, the effect is much smaller than most are making it out to be.