I think the Tupi deserve their own architectural set. The current South American architecture does not properly represent the Amazonian rainforest environment, and the visual language feels mismatched with jungle-based civilizations. Introducing a new architectural style would greatly improve regional authenticity and visual clarity.
This new set would also be highly useful for future civilizations such as the Caribs or Taínos, which share tropical and rainforest environments but differ significantly from Andean cultures. A distinct architecture would help separate highland civilizations like the Incas from lowland and coastal jungle societies.
As for naming, “Tropical American” would be the most accurate and flexible option. While the Amazon and the Caribbean are both tropical, they are not geographically adjacent, and using a name like “Amazonian American” could be misleading and overly restrictive. “Tropical American” better captures the broader cultural and environmental context without implying a single region.
Overall, this approach would strengthen visual identity, improve historical coherence, and provide a solid foundation for future American expansions.