You, inadvertantly I am sure, missed an "adult" Catechism which is in agreement with the "juvenile" Baltimore Catechism albeit with a less wordy version.
Baltimore Catechism
414 Q. What is Purgatory?
A. Purgatory is the state in which those suffer for a time who die guilty of venial sins, or without having satisfied for the punishment due to their sins.
Catechism Of The Catholic Church
1472 To understand this doctrine and practice of the Church, it is necessary to understand that sin has a double consequence. Grave sin deprives us of communion with God and therefore makes us incapable of eternal life, the privation of which is called the "eternal punishment" of sin. *On the other hand every sin, even venial, entails an unhealthy attachment to creatures, which must be purified either here on earth, or after death in the state called Purgatory. This purification frees one from what is called the "temporal punishment" of sin. These two punishments must not be conceived of as a kind of vengeance inflicted by God from without, but as following from the very nature of sin. A conversion which proceeds from a fervent charity can attain the complete purification of the sinner in such a way that no punishment would remain.
* Emphasis mine.
PS. You seemingly overlooked the role of Indulgences to those souls in Purgatory. But I guess that's another story.
Thats why Trent was necessary..to firm up that flow of cash..