There is a certain amount of validity to the “universal language” idea, but it is far from a perfect solution either. In the U.S. and the highly-developed countries it is less of an issue, but in the rest of the world, where illiteracy rates are very high, it is still a huge problem.
The “universal language” idea presumes that a) there are missalettes or some other form of written translation available to everybody, and that b) people are able to read them. Since a good proportion of the world is not literate and does not have written resources available to them, they would be in the dark when liturgy is in anything other than their native tongue.
Is it an issue when we go to another country? I would say less so than when it was in Latin. If one is visiting another country, it is usually either for a limited time, which would reduce the number of times where you might not be able to participate in the responses (though you would almost surely still understand what is going on at any given time). If one is in the country long-term, the need to learn the language will become important anyway.
It also doesn’t wash if the Mass is in Latin. Whether it’s in Latin or the country’s native language you’ll not be able to understand unless you know Latin. And unlike being in your own country, the translation is going to be into that country’s language so it will do you no good at all unless you can at least follow that translation, which again implies literacy.
There just isn’t an ideal solution for the language issue in the long run. I really think the acknowledgment of the literacy issue was a prime reason for the vernacular where at least everyone who spoke the language, the overwhelming majority, would have the most complete access to what was going on and the most ability to engage the the level of participation the Church was seeking. I see it overall as a “greater good” rather than a “lesser of evils” solution though I claim no infallibility on that opinion.
Peace,