I listened to this fairly recently, having worked my way through the archives at a gradual pace. (Almost caught up!) I have to just say, given the relatively middling response, that I loved this story.
I am, as those who've paid enough attention to me to register my comments as something besides random forum noise, exceedingly fond of strong theme and layered meanings, and this story delivered in spades. On the surface, a slightly confusing glimpse of alien politics and a series of amusing answers to the question, "How do you send a diplomat to the future?" Beneath that, however, was a fascinating examination of the nature of anticipation and, I think, religious faith. The diplomats, with all their varying approaches and attitudes and means, all shared faith in the idea of Carthage - that "too beautiful" message whose half-understood power brought them all to the place - and strove in their various ways to be ready for it when it came. The echoes of Christian anticipation of the Second Coming were very loud, in my opinion, right down to the half-vocalized idea that the whole POINT of the Second Coming is that it doesn't come, but is always ABOUT to come. The important thing, as in this story, is to attempt to be ready for it, to aim for perfecting yourself. The desire and actions to improve is the true purpose, not the nebulous future paradise.
The alien diplomats all conform to the seemingly arbitrary rules - with varying levels of literalism in the interpretation, ranging from embracing the spirit of cooperation to communicating only the bare minimum information required. When everyone acts in good faith, however, great strides of diplomacy and understanding can take place. (I'm hardly surprised at the idea that Carthage became a hub of diplomacy; a gathering of high-level representatives in an enforced peace and required to share information freely? It's like Babylon 5...)
I was particularly entranced by the hints of growing danger in the near future, as the waiting grows stale and the hidden weapons are amassed. The title hints obliquely at what might come, when Carthage fails to arrive for long enough and at last someone "loses faith" and violates the laws. (Alternately: The title refers itself to the idea of Carthage, suggesting that this sort of heavy-handed, artificial manipulation of entire races and belief systems "for their own good" is inevitably unstable and will self-destruct.) Perhaps the attackers will even interpret their doctrine to suit, believing that Carthage called everyone there for the sole purpose of enabling the Noble Warriors to defeat their enemies in a single fell swoop... (On the other hand, the story does leave open the idea that things can still be salvaged. I like the sensation of closing the story just before the powder keg explodes and leaving it to the reader to picture the outcomes.)
Basically, I could write an entire scholarly paper on the title alone, and I like that in a story. Five out of five shredded armchairs for this one!