Quote 1
I've heard foreign visitors complain that the Congolese are greedy, naive, and inefficient. They have no idea. The Congolese are skilled at survival and perceptive beyond belief or else dead at an early age. (5.8.42)
The "foreign visitors" Leah mentions are likely other white people who are unaccustomed to the ways of life in the Congo. The Congolese aren't trying to take advantage of other people; they're merely trying to survive.
Quote 2
Most of America is perfectly devoid of smells. [...]Even in the grocery store, surrounded in one aisle by more kinds of food than will ever be known in a Congolese lifetime, there was nothing on the air but a vague, disinfected emptiness. (5.10.8)
Um, we take from this that Leah has never been walking through NYC in the middle of August. Once again, the sense of smell conjures up powerful memories of Africa. Or, in this case, its absence is representative of America, a country which, to Leah, seems to have been dunked in hand sanitizer and left out to dry.
Quote 3
There is not justice in this world. [...] This world has brought one vile abomination after another down on the heads of the gentle, and I'll not live to see the meek inherit anything. (6.2.26)
Here's Leah a couple decades later. Now, she doesn't only believe that the world is unfair, she's believes there's a complete lack of justice in the world. Is she being realistic or pessimistic?