It's equally possible that Deneva (as in the Federation member-state, not the planet) is simply known as Deneva. Not every nation needs some sort of identifier like "united," "republic," "confederacy," etc.
That's certainly possible, though I can't say I like that idea as much. There is a distinction between the state and the territory the state inhabits -- that's why the territory is Germany but the state is the Federal Republic
of Germany: It is the particular federal republic associated with the territory. Some sovereign states today like Canada or New Zealand don't distinguish between its state and its territory, but I can't say I much agree with it.
And the distinction between the state and the territory is particularly notable given Deneva's eventual, er, destiny. I can't help but think linguistically conflating the Denevan state and the planet Deneva will only make the eventual need to relocate even more linguistically awkward than it might otherwise be.
there seems to be some sort of affinity attached to the colonial identity in the 22nd Century that prompts some former colonies to keep the word in their name.
I suppose in an age of interstellar travel the word carries connotations of "boldly going", of brave pioneers and forward-thinking explorers. People are proud to be known as "colonists", who built their settlements through hard work or that of their direct ancestors, rather than simply inheriting a fully-realized planetary infrastructure?
Makes sense!
* * *
Random musing:
We know the heads of state and government for most of the founding Federation Members...
United Earth is a parliamentary republic, with a ceremonial President (
ENT: To Brave the Storm) and a Prime Minister who is the real leader of the state (
ENT: The Good That Men Do; Kobayashi Maru; Beneath the Raptor's Wing), and a Parliament as its legislature (
ENT: To Brave the Storm).
There is the Administrator of the Confederacy of Vulcan (
ENT: The Romulan War: Beneath the Raptor's Wing), which succeeded the office of Administrator of the Vulcan High Command (ENT: "The Forge"), which was dissolved when the High Command was dissolved (ENT: "Awakening"). For a brief period, the Administrator of the Confederacy seems to have been initially known as the First Minister of the Confederacy of Vulcan (
ENT: Kobayashi Maru) before the name of the office was settled on as "Administrator." We hear reference to the Vulcan Council in ENT: "These Are the Voyages...," and in
ENT: The Good That Men Do and
ENT: Kobayashi Maru. Seemingly this would be the Vulcan legislature?
We know the Andorian set-up very well. The Andorian Empire (ENT: "The Andorian Incident") is a constitutional monarchy, with the office of head of state left as the Empty Throne (named after a religious artifact within the beliefs of the most common Andorian religion, Uzaveth worship), the unfilled monarchy left by Thalisar the Last in the 19th century, who united Andor into a parliamentary democracy under the Monarchy and ended clan warfare (
Andor: Paradigm). The legislature is the Parliament Andoria (
Andor: Paradigm), and the head of government is the Presider of the Parliament Andoria (
Andor: Paradigm;
The Fall: A Ceremony of Losses), elected by the Parliament from among its members according to which MP has the confidence of the majority of the Parliament (usually equaling the leader of the majority party or of the largest party in the governing coalition) (
Typhon Pact: Paths of Disharmony; The Fall: A Ceremony of Losses). The office of Presider seems to have been translated into English as "Chancellor" back in the 22nd century (ENT: "The Aenar"). Political life is dominated by the Modern Progressive and Visionist Parties, with there also being several smaller parties that are either further to the political left or the political right than the two main parties (
Typhon Pact: Paths of Disharmony).
We know that the Alpha Centauri Concordium (
ENT: Rise of the Federation: A Choice of Futures) is led by a popularly-elected Governor (
TNG: Losing the Peace). We have no information on the Concordium's legislature.
So of the founding members, that leaves us with one where we don't know its basic constitutional framework -- Tellar! All we really know about them is that their state is known as the United Planets of Tellar (
A Choice of Futures,
Tower of Babel). Are they led by a President? Governor? Prime Minister? Chancellor? Minister for the General Administration of the Cabinet? Elder of the State? Minister-President? Sultan? Statsminister? Chief Magistrate? Taoiseach?
And what of the Tellarite and Alpha Centauri legislatures? Do they have Congresses? Parliaments? General Assemblies? Diets? Councils? Dumas? Majlises? Senates? Houses of Delegates? States-Generals? Althings? Oireachtases? Folkmotes?
Inquiring minds want to know!