I was going by the fact that Bolivar was Venezuelan and that Venezuela was created before the other states, and the base from which Gran Colombia expanded - Bolivar created Gran Colombia from a Venezuelan base. That he then relocated the capital I don't think is particularly significant - that prompted the modern Colombian state to treat Bogota as its capital, but then Indonesia adopting Dutch Batavia as its capital Jakarta doesn't make Indonesia a direct successor to the Netherlands.
I think calling Gran Colombia a "Venezuelan empire" is a bit misleading for a variety of reasons. To begin with, the Fundamental Law of the Republic of Colombia, the act that founded the Republic of Colombia (Gran Colombia) in the Congress of Angostura of 1819 stated the following in its first article:
"Article No. 1. The Republics of Venezuela and New Granada are united from this day forward in a single republic, under the glorious title of Republic of Colombia". Legally, Gran Colombia was an union of two previously existing states, similar to how the United Kingdom was created from the union of England and Scotland. Under the law of Gran Colombia, the former citizens of the previously failed republics of Venezuela and New Granada became Colombians, in the same way as English and Scottish people are legally British citizens.
Moreover, Colombia was a termed coined by the Venezuelan Francisco de Miranda, who fought in the American Revolution, since at least 1800 to refer to all the Spanish territories in the New World and to its citizens, all the way from Spanish Louisiana to Argentina. Bolívar's idea, influenced by Miranda's idea of a Colombian identity that encompasses all of Spanish America, was to form a single country under the name of Colombia. For him, all Spanish colonial citizens should belong to these state. Under the Constitution of Gran Colombia,the particular identities of the territory (Venezuelan, New Granadan, Quitoan, etc.) where treated as regional varieties of a single Colombian nationality. To say that Gran Colombia was a Venezuelan empire is like saying that the revolutionary United States was a Virginian empire because Washington was born in Virginia.
Simón Bolívar's army consisted of soldiers from both Venezuela and New Granada (modern day Colombia), which joined him after escaping the Spanish reconquest of the independent states of Cundinamarca (founded in 1810), Venezuela (1811), and New Granada (1811). Bolívar's second in command, General Santander, came from modern day Colombia. In this sense, the independent state of Cundinamarca (modern day Colombia) was created before the First Republic of Venezuela, and then joined the Republic of New Granada in 1811. Also, Gran Colombia expanded from New Granada (modern day Colombia) and not from Venezuela. Proof of this is the way in which Bolívar's army first secured the independence of New Granada and captured its capital, Bogotá, after the Battle of Boyacá in 1819. He did this in order to secure more people and resources to then launch campaigns to Venezuela (Battle of Carabobo, 1821), Quito (Battle of Pichincha, 1822), Perú (Battle of Ayacucho, 1824) and Bolivia. Gran Colombia was a joined effort by Venezuelans and New Granadans (modern day Colombians) to liberate their territories and incorporate other Hispanic cultures into a single identity known back then as Colombian.
Bolívar's choice of capital as Bogotá was not random. The city had been the capital of the Spanish colonial viceroyalty of New Granada since 1717 and of the New Kingdom of Granada since the 1540s, which included the colonies of the captaincy of New Granada (modern day Colombia), Venezuela, Quito (Ecuador) and Panama. All Latin American countries who got independent based their borders and territorial claims on the principle of
utis possidetis, claiming that the territories of their new countries corresponded with the administrative divisions of the former Spanish colonies. If Bolivar settled in Bogotá, he could then claim by virtue of this principle that the rightful territory of Gran Colombia was the territory of the former viceroyalty of New Granada, whose capital was in Bogotá.
Two views exist after the dissolution of Gran Colombia in 1831. The first one is that Venezuela, Ecuador and New Granada (later modern day Colombia) began from scratch and that they were new countries from that point onward. The second view is that Venezuela and the Ecuador separated from the Republic of Colombia (Gran Colombia), which then had to make a new constitution, in which it changed its name back to New Granada, to reflect this reality. In this last view, New Granada, which then reacquired the name of Colombia in 1863, is considered the legal successor of the Gran Colombia (Republic of Colombia) which is the reason why the Constitution of 1886 reestablished the title that the country currently has: Republic of Colombia. For this reason, the modern day Republic of Colombia assumed the responsibility of the foreign debt, foreign representation and most international treaties that the first Republic of Colombia (Gran Colombia) had acquired during its existence.
Sorry for this long and complicated explanation, it really is a complex issue and I think that it important to know this to understand why the developers decided to select the name Gran Colombia for the new civ in the game. The meaning of the word Colombia has changed a lot throughout history. From the late 1790's to 1819 it meant the union of ALL Hispanic Americans in both North and South America. Between 1819 and 1831 (during the existence of Gran Colombia) it meant all the citizens of the three states of this republic (Venezuelans, New Granadans and Ecuadorians). Between 1831 and 1863 it became an old word to refer the union that existed between Venezuela, Ecuador and New Granada. Between 1863 and 1991 it meant free white and mestizo citizens who could vote (excluding Afro-Colombians and indigenous people) in the United States of Colombia and the current day Republic of Colombia and finally, since 1991, the word Colombian meant everyone born in the modern day Republic of Colombia. For this reason, using the term "Colombian Civilization" for the game would have been extremely ambiguous in a game that has a historical scope, not just based in modern day names and politics.
However, the term "Gran Colombia" has the modern connotation of a union of the modern day countries of Venezuela, Colombia and Ecuador (in some contexts Panama as well). It has become a common term for all the peoples of these three (four) countries. For these reason, I think that the Gran Colombian Civ that is going to be included should not be seen just as a big country that lasted less than 23 years, but as the culture that emerged from the Spanish, Indigenous and African groups that settled in what is today Colombia, Venezuela, Ecuador and Panama. A culture that began to form way back in the 16th century when Bogotá was founded by the Spanish and that acquired its first independent and largest form under the Venezuelan Simón Bolívar, during the duration of Gran Colombia, but which continues to exist to this day under these four nations and their shared history, culture and even founding ideology, which had a profound impact in the creation of modern day Latin America.
In summary: "Colombian civ" can be ambigous for a historical game, "Gran Colombian civ" can be more inclusive and represent the people of four currently existing countries, not just modern day Colombia, and it can be argued that Gran Colombia as a state ceased to exist or transformed into modern day Colombia, but its culture and influence still form part of the identity of more than 100 million people in Venezuela, Colombia, Ecuador and Panamá, surely a society/culture/"civilization" that is still struggling to "stand the test of time" to this day.
(Sorry for the length of this post, I thought it was important for you guys to have the perspective of someone from the modern day Republic of Colombia and I apologize in advance for any bias I could have had when I wrote this due to me being from Colombia).