The UN rejected completely and utterly this bogus claim for self-determination with respect to the Malvinas as far back as 1965. You cannot claim self-determination if population was sent to the islands for the purpose of establishing a colony.
Let's review:
In 1764 - France established a settlement, Port St. Louis, at Isla de la Soledad. Two years later the British claimed the islands and established a settlement at Port Egmont. That same year France transferred their rights to Port St. Louis to Spain. In 1774, the British withdrew from Port Egmont for economic reasons. Spain did not withdraw their settlement until 1811, and by 1810 sovereignty transferred to Argentina. A permanent settlement was established at Puerto Soledad.The UK did nothing to challenge Argentine sovereignty until 1829. From 1820-1829 Argentina exercised full sovereignty over the islands without any challenge.
In 1831, Americans were arrested for poaching seals off Argentine waters near the islands. Americans responded by destroying the defenses of Puerto Soledad and declaring the islands res nullius. In 1833 took advantage and seized control of the islands, evicting the Argentine authorities and its settlers.
The Argentines have challenged British control of the islands unceasingly since 1833.
In 1834 the Argentines attempted to reopen the question. In 1841 it said that there was no proof that Soledad island ever belonged to the British Empire. Argentine entreaties continued until the United Nations declaration 2065 which said that the two sides should negotiate for the decolonization of the islands in 1965, a declaration the UK seems content to ignore now. They didn't ignore in the 1960s. In 1967 they agreed in principle to the idea of transferring sovereigty in exchange for the islanders interests being secured. The problem was this agreement was leaked to the press which evidently caused much embarassment to the UK government. A "Falkland Islands" lobby was created to prevent the transfer of sovereignty, and the British scrapped their memorandum of understanding. The British then gave the islanders a veto over any agreement made with the Argentines.
So your sole argument here is because the British refused to negotiate for basically 50 years after their forceful takeover, and did not negotiate in earnest until the 1960s, and Argentina has not had the maritime power to take on the British Empire, this is a "self-determination" issue. It's as if a bunch of people evicted the inhabitants of homes with guns, squatted on their homes for a long period of time ignoring any protests, and then they get to cry about "self-determination" once sufficient time has elapsed It's a bogus argument and the only reason you're making the self-determination argument is to manipulate anti-imperialist rhetoric for your own settler colony. It's a cynical tactic and it's not going to work.