Jesus became man, suffered, died and rose for the salvation of everyone, regardless of whether or not they speak the predominant language of the country they’re living in. And the Church has the mission of spreading the Gospel to everyone, everywhere, not just the native speakers. If that is better served by having Masses in multiple languages, then by all means let it happen.
Like many others I’m sure, I’ve had the opportunity to live abroad for a while. In my case, I was in France, and went to churches where French was spoken. My ability to understand spoken French was sufficient to understand what the prayers and the readings were, but that was mostly by catching a few words here and there, and figuring out what the corresponding English prayers/readings were. When it came to the homily, I was totally lost. After a few months of my “exile”, I returned home, and I found it a great joy and comfort to once again hear the Mass in “real time” without mentally translating into English, and to be able to understand the homily, and not to be embarassed at my horrendous accent when exchanging the sign of peace.
So with that experience in mind, I think of what it must be like for folks who, for whatever reason, are in a foreign country for many years, and what a great comfort it must be to hear the Mass in their own language, and to have a homily they can understand well enough to help them in their spiritual lives.
Going back to all Latin will not totally solve this - people will pick up enough to understand the prayers, probably not the readings, and the homily will still be delivered in some vernacular. I don’t like the idea of large segments of a given parish never fully understanding the homily. That sounds more divisive to me than having multiple communities with different languages.
By the way, the multiple language thing in many parishes is often a result of shifting neighborhood demographics. 80 years ago, a neighborhood may have had primarily Polish speakers. We still have some recent immigrants from Poland, as well as some of the old-timers and 2nd generation Americans who speak fluent Polish. But now we also have the 3rd or 4th generation Americans who no longer speak Polish. Many of the Polish have moved elsewhere, and there is a large influx of 1st generation Hispanic immigrants. Hence a parish that used to serve only Polish speakers now serves Polish, English, and Spanish speakers.