QUAERITUR: licit use of languages for Mass

From a reader (edited):

I am at the [organized thing for seminarians] for the summer and each Friday Holy Mass is celebrated in Spanish.  In my estimation, about 20-40 out of 173 seminarians here this summer spoke spanish as their mother tongue, but everyone here is fluent in English.  My question is, can Mass be licitly offered in Spanish here at [organized thing for seminarians], whose working language is English?  Is my interpretation of vernacular (the everyday language of the local people or institution) too strict?  If I do have the correct definition of vernacular, it would seem that the only licit options here would be to celebrate Mass in Latin or English, as Spanish is not the vernacular of [organized thing for seminarians] or [this city].

Yes, I believe it would be licit to celebrate Spanish at that organized thing for seminarians in that city. It is licit also to use English.  Those languages are permitted exceptions to the official language of Holy Church’s liturgy in the Latin Rite.  It would also be licit to have Holy Mass in Tagalog, Hmong, or Swahili.  It would be silly to have Mass in those languages for that crew, but it would be licit.

It seems to me that a more inclusive approach at this summer thing for seminarians would be to have Holy Mass in Latin.  The seminarians could use whatever language resources they would need to follow and they would get some exposure to the language of their Rite.  Furthermore, no favoritism would be shown to any group.  Finally, I am guessing that, as seminarians, they may be a little familiar with the structure of Holy Mass.  I don’t think it was be overly challenging for them to figure our what is going on.

C’mon, people.  More Latin in the Latin Church, okay?