Drupal rocks, we all know that. But for non-english speakers (french users in our example, but this is not restrictive), whereas a basic drupal installation in their language is now a basic, when it comes to "can't live without them" modules, UI is often only in English. When a big institutional customer has to benchmark different CMSes, this can plague drupal.
When a small community is under pressure of a larger dominant culture, what can they do? Language has always been a major element for building a society's identity and it is not different for indigenous peoples in Brazil. If a language have less space and less space in its speakers' lives, it will shrink and may become endangered. To avoid it, one must seek all available resources to strengthen minority languages and give them more room to grow.