I attended an Acadian Reunion in 2009. The Mass, Hymns and Homily were in French, and I remember thinking as you say, of the Universality of the Church, all united in Faith.
When I was I college, I took French. it was a Catholic college. The professor insisted we buy French-language missals for Mass. On one side was Latin, on the other side was, not English, but French. Why did he do that?
Because by that time, we were so used to the Latin that we all knew what it meant. We really didn’t need the English translation anymore. And so, in order to know what the French said, we were “translating” from Latin into French.
Today in my parish we have a Mass in Spanish. I can sort of understand the Spanish because I learned the prayers in Latin a long time ago. Spanish isn’t all that far removed from Latin. But for that, and the fact that some Spanish words have a French equivalent that’s spelled the same or nearly so, I would not understand any of it.
My adult daughter attends the Spanish Mass most of the time because of transportation issues. At the Spanish Mass there are also no few Central Americans who don’t speak Spanish but some Indian dialect.
I have read that in big cities the Mass might be said in ten or more languages.
I fail to see the harm in a Latin Mass. Most people will understand a lot more of that than they will of Vietnamese, Albanian, or Aguateca.