The problem is that I simply can't see how these Republics could even become independent. The Juliana Republic was a kind of joke. It consisted of only one city (Laguna), lasted only four months, and the rebells managed during this time to piss off most of the population of the region and ruin the local economy to a point that Laguna never recovered the importance it had before the war.
The Riograndense Republic lasted many years, but frankly, the rebells where divided about actually becoming independent of just supporting a federal republic with the other Brazilian provinces (most of them actually had nothing against the Empire, just wanted Rio not imposing them higher taxes). Also, they never managed to hold the main cities of the province (except for Porto Alegre, that was conquered for a few months in 1835, they never entered either Pelotas, that was the richest city, neither Rio Grande, the only port. The war only lasted 10 years because the central government was more worried about other more important rebellions in the North. Once the Northern rebellions were put down they focused on Rio Grande do Sul, and then the rebells had no chance.
The "farrapos" could have a slim chance of winning if they had received support from Argentina and Uruguay, but that was a game they didn't want to play. When the Argentines finally asked them if they wanted armed support the leaders of the rebelles informed Buenos Aires that "the first of your soldiers who cross the border will give us the blood with which we'll sign the peace with the Imperials". After all, they hated the "Castilians" more than any monarchist.