While the map looks great, I don't think it accurately represents the Tamoyo Confederation. The Confederation was along the southern coast of Brazi (the most specific information I've found equates the Confederation, roughly, with the area east of São Paulo through the entire state of Rio de Janeiro; but if
this map is accurate, that area seems to be maily for the Tamoyo themselves, not the whole confederation, which would extend through Espirito Santo and along the coast of Bahia, based on known members of the confederation). Regardless, itt didn't extend too far inland, and it didn't include every Tupi-Guarani group. Of course, that's my understanding of the situation. Finding English-language sources on the topic has been hard. I've mostly been relying on Portuguese sources that I can force Google to translate for me.
I'm actually considering the whole part of making the Avá (Guaraní) as a civ... I was getting some interesting ideas; mostly centered on the whole interesting and artistical interaction with Jesuits too. The whole thing of using Guarani, was because Guaraní actually means Warrior anyway.
As I'm sure you remember, I'm in favor of splitting the Tupi and the Ava up (or least making the Tupi in such a way that they don't eliminate possibility of an Ava Civ later, even if no one gets around to making one any time soon).
UI: Mission: Built by Missionaries it consumes the missionary when built. May only be built on Jungle and not adjacently to another; +3 Culture; +1 Culture after the discovery of Accoustics.
I think this steps on the toes of the Jesuit Missions you're planning for Paraguay, and I prefer it as a Paraguayan UI rather than an Ava UI.
Of course, if you could someone how make the Mission into a UI improve you can acquire through choosing a specific, new Religious Belief, that'd be awesome and probably the best way of handling it. Barring that, I say give it Paraguay and give the Ava something that wasn't thrust upon them by their colonizers.
Also... what would be a good capital for the Tupi?
Iperoig, definitely. It's Cunhambebe's town and the place were
the peace treaty between the Tamoio Confederation and the Portuguese was eventually signed.
Since I'd prefer to keep this Civ as closely associated with Tamoyo Confederation as possible (rather than being a Tupi-Guarani blob -- not that I have any say in the matter, just my opinion here obviously), here's a list of potential city names from the region (roughly from Cabo Frio to Bertioga, since that's the area that was certainly part of the confederation), in no particular order:
Quick research! So, yeah the Guaraní did use wooden cannons in those wars; made of Tacuarazú. They were not as effective and were not too wide though; so in fact its almost like having big muskets instead of an artillery in a way. Still... it would be fun; a non-artillery cannon replacement.
Any opinions on the UA and UI for the Avá/Guaraní?
I love the idea of using the cannons as their UU, so definitely go with that.
I like "A Land Without Evil / A Land With No Evil" as the name of their UA, but I dislike tying it to the Jesuit Missions. The whole "Land Without Evil" concept is part of the Ava resistance to colonialism. Giving them stronger resistance to Foreign Religion and Foreign Tourism and / or increased Attrition for Foreign Missionaries and Prophets would be thematically appropriate, but might be too passive for fun gameplay.
As for a UI, I recommended the
Tekoá, but it may be too similar to the Maloca for the Tupi. Alternatively, you could go with the
opy as a UB.
About the Guaraní. The leader would most likely be Sepé Tiarayú
Sepé Tiarayú is a great choice, given his prominence in Ava culture. My previous recommendation suggested
Nheçu, with
Inhacurutum as his capital. Sepé is probably a better choice, but Nheçu came with a convenient capital.