Paraguayan, living in Asunción. Interesting, yet a bit simplistic, take. Things in Paraguay are much more complex and nuanced than they seem at first sight.
Asunción downtown is "incoherent" as the OP said, but one of the factors is that most historic buildings in it are concentrated in the hands of a very few landlords. The buildings, since they are historic, cannot be demolished, and property taxes for downtown are quite high. So, the landlords leave them to rot, building new things after the buildings fall down due to neglect, taking advantage of the fait accompli.
That remark about "con factura or sin factura?" (invoice or no invoice) is not longer a thing. Most businesses now give you a legal invoice as a matter of course.
Anyway, nice to see my hometown featured on HN.