Here's my Flags entries!
Chinon: Chinon is - we can assume - Asian countries, engulfed by communist China (given the hints of dramas in Tiba). So for their flag, I've used the Chinese flag's colours (red/yellow) and incorporated symbols used in the Japanese (sun), Vietnamese (star) and Korean (the angled lines in each corner) flags.
Gadfia: Gadfia is tricky...it's Africa, Mid East, and South America from what we're lead to believe. The fact that it's called Gadfia (I'm assuming after Colonel Gaddafi, the old Libyan leader) leads me to assume the dominant old-world power in the conglomeration is the Mid-East. When looking at the flags of the mid-east today, they all use pretty much the same red, white, black and green colours, with few exceptions. The Gadfian flag is split up into nodes to try indicate the different stretches of land that it encompasses...but TBH, I found depicting something to represent these guys really difficult.
Mericanda: From it's name, we can assume Mericanda is a merging of America and Canada. So the flag is simply a merging of the two as well; red and white stripes, blue background, and instead of the stars / maple leaf, a massive top section of a maple leaf (Canada), that looks a little like shooting stars at that size.
Tipoda: This one was the easiest for me for some reason :P
Tipoda's all of the islands in the Pacific, right? So, their flag has to be blue and green; symbolising that the nations are all islands. The southern cross is used in so many Pacific flags (not to mention that Australia and/or NZ are likely to be the dominant power in the merging) that it felt wrong to exclude it, so that's why it's there.
Uropa: This one was hard only because Uropa kind of exists already - as the European Union, and they have a flag :P (blue bg, yellow circle of stars). But then I remembered...the UK don't really count themselves as a part of it. So a proper merging of all of Europe would undoubtedly include a portion of their flag (the red and white stripes - sort of like a piece of the Union Jack). But surely, if GB got to have a bit of their flag, some of the other major European countries would want a piece of it - so I've added the green, black and yellow as nods to Italy and Germany, too (I figured France was covered with the red, white and blue already).