Catholicism was defined at Trent? What an utter insult to 1,500 years of Catholicism that came before it and 500 years that has come since! What an utter insult to those Eastern Catholics who have NEVER worshipped at a TLM, and never will!
How many of our vital Catholic dogmas and beliefs did Trent define? Papal Infallibility? the Immaculate Conception? the Assumption? Transubstantiation (ok, maybe

)? Mother of God? The Trinity? The Hypostatic Union and dual nature/single personhood of Christ? Mary’s Perpetual Virginity? Intercession of the Saints? The Canon of the Bible maybe? Don’t think so.
Heck, did it even deny the validity of 1,300 years of liturgical plurality as well as development (including linguistic development - some of the older liturgies are in Greek among other languages) that occurred before the Council?
No, it embraced that development, and that plurality, when it a) permitted those liturgies that were more than 200 years older than the TLM to continue and b) didn’t impose the TLM, or Latin, on Eastern Catholics.
Perhaps a bit of my background might help you to see where I’m coming from. My family are Croatian. Croatia for a good century or more prior to Vatican 2 had an indult to say Mass in a different liturgical language entirely - Old Church Slavonic. In fact it was FORBIDDEN to mix Latin into this Slavonic liturgy! Quite an extraordinary concession, and an even more extraordinary command accompanying it, to have come from Rome if Latin truly is the
ne plus ultra!