I have no issue with a Spanish-speaking person calling them Las Malvinas, since that is the name for them in their language, being an adaptation of the French name Les Malouines.
The Argentinean insistence that people should call them Las Malvinas when speaking English, is a deliberate political attempt to impose their name for them over the name the inhabitants use, and thereby obtain a reduction in the perception of legitimacy for the autonomous, democratic Falkland Islands government. The Falklands have just the same status as several places in the West Indies, etc. They are self-governing in all areas but defence and foreign policy, and have not taken full independence. But then neither have Montserrat, Anguilla, Bermuda, British Virgin Islands, Cayman Islands, Pitcairn Island, Turks and Caicos Islands, Tristan da Cunha, St Helena or Ascension Island. But generally speaking other nations respect the right of the occupants of all those other places I mention, many of which were colonised in just the same way as the Falkland Islands, to govern themselves and choose not to take full independence from Britain. There are places in the world which regret having taken full independence - the Comoros invited the French back, but they refused.
People go on about "decolonisation". But the Falkland islands have substantially been "decolonised" in just the same way that Argentina or New Zealand was "decolonised", ie, government of the territory passed from the colonial power to the colonists. This was in some cases in South America an opportunity to increase abuse of the native population, which the Spanish crown sought to impede.
When I have been in Argentina, I discover that few Argentineans are aware that the Falkland Islands are a self-governing territory. They were very interested to see the stamp in my passport that admitted me for only two weeks. They thought it was an integral part of British territory, like Ireland before independence. Amusingly, when the issue came up on "Any Questions" on Radio 4 on Friday, all of the panelists seemed equally unaware of this, talking of the Falklands as "ours". They aren't, they are the Falklanders'. "What do you learn in school about the Malvinas", Argentineans would ask. They were astonished at the answer "nothing". In Argentina, despite democracy, history lessons still involves rote learning of national positions on various historical issues (or it did 10 years ago when I was shown history texts and sample exam papers.)