In my earlier days I was fluent in three languages. This proved essential for understanding other peoples and their cultures. Language is the link between people that promotes understanding. Language contacts are increasing rapidly in today's world. English has become the lingua franca of the West and also in other parts of the world visited over the centuries by western missionaries, explorers, tourists, and conquerors.
Latin became the unabashed tool of the Romans. They controlled the conquered territories by promulgating Roman institutions through their use of their language. In this way, lawfulness and cooperation among disparate peoples led to community efforts to build physical and cultural projects that are the mark of civilization. Language became the means of governing, but there were losses, too. The Celts, and the Vandals, and the Goths all became "Romans." Was this spread of Latin a curse or a blessing? Probably both.
The national level of cooperation found today in in India would not have been possible without a lingua franca, which it turned out, was English. The progress of westernization was incidental to the imperialistic intent of British colonialism of its time. So colonization is not altogether bad, but does it bring losses of local cultures with it? Of course!
Less clear are the benefits brought to the Middle East by the Crusaders and the subsequent colonizers. Invasion and the introduction of a foreign-language link subverts the local culture and government. Disruption of the local religion is accomplished by importing western religious systems into the region. After all, reading of the Bible (in English) is necessary for all who would be saved! The British imposed western, Christian institutions on the Middle East on the heels of the Crusaders.
The French were even more determined to see the blossoming of their legacy of Crusader intervention. The residuals of crusader conquest are still found clearly in the Lebanese group called Maronite. Despite their long Arabic history and background, they pretend to be Europeans (French). They have their own French-based Christian church and they deny that they are Arabs. Instead, they claim to be Phoenicians and they only speak French within their community. Today they remain a strong political force in the Lebanon and they usually work against Arabic and Lebanese political unity.
But, while French influence in Lebanon is circumscribed, not so in North Africa. After World War I, France took over colonial power in the countries established by the West and now known as Algeria, Tunisia, and Morocco. All administration and education was in French. Arabic was systematically eliminated and all government procedures were conducted only in French. After decades of occupation, many people no longer speak Arabic and even fewer can read their own language. It is still necessary to continue conducting many government functions in French. Needless to say, the local religion of Islam has been suppressed.
The Spanish invaded and colonized the new world. They brought their language, religion and smallpox with them. Now, in modern days, Spanish is the lingua franca of part of North America (Mexico), all of Central America, and all of South America, except for Brazil. The lingua franca seems to have been of little benefit to the region. Governments seem to be dedicated to Western control rather than to international cooperation. The universal Spanish language, integrated with the religion provided the opportunity to govern the people in the autocratic pattern set by priests.
Conclusion? Foreign language training is a two-edged sword. It can and will be used to help improve the lives of the people but also will destroy certain aspects of their community ways. You may trust your particular school or organization to have good intentions and to do more good than harm. But what about other schools? What about the future educators? And what about present and future politicians, who will seek any advantage to reach selfish goals?