Why did the series not sell in Amerika? Well, maybe because it promotes smasshing down anyone who wants to break free from your empire, and because in all books translated, empire is a big, good and natural thing. And then there is the thing that at the start, the message is that niether Russia nor America is really better than the other, and they just have to live together in peace. Try telling that in the middle of the Cold War!
In the series, humans are totally broken. Their scientists solve things in months what other have been trying for centuries. They steer ships better than the best AI. They improvise so well it even gets lampshaded. And their bureaucracy isn't even that bad! How does this work, why is Earth so amazing? It seems weird, until we learn that all species are descendents of the Terran Lemurians. In the series, colonial races are always less good than their parents. Akons are way more active and advanced than Arkonids, who still do more than their colonies. So if Earth was the birthplace of all life, it makes sense they are the most active, have the best scientists and rapidly rise to power.
Why hasn't there been more translated English adaptations since the 1970s? There have been a few since but they were very short lived. It may be due to the fact that Perry as a character is just not that relatable to more modern readers. He is, without a doubt, a HeinleinHero turned up to the max. Except for Batmannote Batman had a good reason to be reimagined early on as hypercompetent. He needed a justification for inclusion among Superman, Wonder Woman, Green Lantern, and other truly superpowered hereos., such hypercompetent characters are generally not that popular except to adolescent male readers. And unfortunately, outside of very nostalgic adults (who wouldn't mind the Values Dissonance and who would probably be again, mostly male), that would likely be the majority of Perry fans.
