Always read VERY carefully when you read the documents of Trent. ALWAYS go look up for yourself whatever someone else quotes. Always look to the EXACT phrasing of the text.
The anathema in question relates to “faith alone,” exclusive of living out the Christian faith in practice. Read the language of that article again. It means that if anyone says that justifying faith is merely “confidence in divine mercy” and nothing else – no living it out, no faith beyond “confidence”, and that such “faith” only justifies, and not the Person of Jesus Christ, by grace through faith, then the anathema is invoked.
This article states that the doctrine of “faith alone” as articulated by some reformers is not the Catholic faith, is not “justifying faith” and that anyone teaching such a thing is teaching falsehood. Hence, the anathema.
Your evangelical friends should not take offense that the Whore of Babylon rejects their novel soteriology. They should look at Trent as the perfect culmination of their worst suspicions about us Catholics. Refer them to the Catechism of the Catholic Church. It says the same thing but in positive rather than in negative language.