The Catholic Church formed the "Council of Trent" to try to address problems within the Catholic Church. Where on the timeline should this be placed?

You didn't show a timeline, but I'll give you the dates.

The Council of Trent was held over a span of years from 1545 to 1563. This was held following the events of the Protestant Reformation.

The Council of Trent served to reform some abuses that were acknowledged by the Catholic Church. Mostly, though, the Council aimed to assert the full authority of Roman power and doctrine over the Protestant threat. The Protestants' teaching of sola fide ("faith alone") was resoundingly rejected by the Council of Trent.

In terms of problems addressed by the Council of Trent:

Indulgences had been attacked by Martin Luther in his 95 Theses, as the catalyst that started the Reformation movement. In regard to indulgences, the Council of Trent upheld the underlying principle - - that the church had authority to grant reprieve to penance or time in purgatory. But the sale of indulgences was stopped. The church recognized that the selling of indulgences had been an abuse and determined to end that practice. Weaknesses in clergy education were also addressed by the Council of Trent. Seminaries were established, and the Roman Catechism, also known as the Catechism of the Council of Trent, was commissioned by the Council and was published in 1566, with the intent of thoroughly educating the church's clergy.