The answer is straightforward. They are a coalition of Brazilian labs (click on the link in the first sentence to get more information) so it seems normal that they would be focusing on the research conducted in their country. Also it is not the first research of its kind as the nature article provides context

> The teams were able to replicate the results of less than half of the tested experiments1. That rate is in keeping with that found by other large-scale attempts to reproduce scientific findings. But the latest work is unique in focusing on papers that use specific methods and in examining the research output of a specific country, according to the research teams.