As soon as a coin in the coffer rings, a soul from purgatory springs!

The CONSEQUENCE, not the sins, is effaced.

The detachment from sin is only required for a PLENARY indulgence. And what it is, is simply a complete rejection of sin and of any desire to commit it.

The whole part about "The treasury of the Church" is horrible. Do Catholics really believe this?

Yes, they do. Or they should. All the saints have treasure in heaven (Mat. XI, 20), which is the accumulation of the merits of all the good works they performed during their life. Jesus, of course, has the great and infinite treasure for His sufferings and death on the cross. His merits, and that of all the saints, can be applied to those who have been forgiven their sins but are still left with a debt to pay, of which they will not be freed until they have paid the last penny (Mat. X, 26).

Just to be clear here. Are you saying that this is some kind of point system where the saints have accumulated points by their good works and we can draw from these?
This turns sin into a debt to pay, not a disease to cure. This is more akin to a Buddhist karmic system than to any shape or form of Christianity.
To say that we must fulfill certain things to receive this grace, as if it were an achievement system, is even worse.
Please tell me I am misunderstanding this.

A Catholic monk is the father of modern accounting if that helps.

Why are you trying to trivialize this by referring to merits as "points" as if it was a mere game? All are works have a value which is weighed by God who repays all according to what they have done (Rom. II, 6). When we get to heaven, our good works will receive a specific reward depending on what they were (Jer. XVII, 10). So, no, it's not a "point system", because we're not talking about a game here, but rather the eternal rewards of our life's works given to us by God.
Sins have both an eternal and temporal consequence. We can be cured from our spiritual illness, but the consequence of the evil we have brought on the world remains. God wants us to do penance for our sins (Mat. III, XVIII), and by this satisfaction we pay back the debt of our sins which are also weighed by God.
What do you mean? Those "things" are meant to first free us from the eternal consequence of sin. How can you be freed from the temporal when the eternal remains?

Maybe because that's exactly how it sounds like from the article you sent me.

But so far you have been talking about indulgences being granted right here and now if we fulfill certain actions while being in a certain state. Now you're talking about the abode we will receive in Heaven? That will be granted to us upon our death, not here and now (even if you say we can lose an indulgence by ceasing to be in a state of grace for instance).

But we aren't indebted to God. The debt we have contracted was with Adam's sin, and Christ lifted this debt for the whole world, which is why all will be resurrected.
Penance is given for our personal well-being and progression toward theosis, not to satisfy some debt toward God.

What frees us from the eternal consequence of sin is the Eucharist, received in a proper state thanks to baptism, chrismation, and confession. I don't see what else needs to be said.
Why do you say that particular actions must be carried out in a particular state for the "temporal consequence of sin" (I assume you mean worldly attachment by this)? From my perspective of a flawed and stupid sinner, it sounds like boxes to be checked, rather than a relationship with God fulfilled in prayer, fasting, and almsgiving.

Wtf?

Do you really think you don't have to do a penance for your sins? Emend the crap we did? Not doing anything is of course the easiest path.
Imagine if you hurt your wife's feelings for example. You will apologise and I'll try to make up for her.
Same thing with God. Everytime you sin you hurt him deeply, and you must show him you truly regret and try to emend yourself by doing a penance.
Jesus sacrifice opened for us the doors to heaven. He was the way for us to get rid of the sin of Adam and Eve. This doesn't apply to every sin, otherwise a Christian wouldn't sin and he would be in the original state of Adam. We sin and we must do penance for them.
Adam's sim was so bad that animal sacrifices weren't enough. Only the Lamb of God was necessary for the ultimate sacrifice. Nowadays anyone who follows christ can get to heaven, as opposed to Jews that couldn't get there before Jesus opened the doors.

Honestly, if you weren't willing to entertain the catholic viewpoint to begin with then you should have said so earlier because this has been a complete waste of time

Purgatory but since you're an orthodox this won't mean anything to you. user was right.

Yes, we must repent. This is fulfilled in the sacrament of confession. Penance is given after confession to build up our soul and our body against sin and worldly attachment, not to pay a debt.

Do you believe the sacrament of reconciliation alone is not sufficient to do this? Why?

I'm not arguing against Catholic theology, I'm asking for clarification on a doctrine I don't know about.
Besides, weren't we in communion for 1000 years? Don't we read from the same Bible? Catholic and Orthodox theology have the same basis and the same gospel, what separates us is the interpretation of history.

What is this supposed to mean? To attain some higher "plane" like oriental philosophy? To achieve the theosis?
If you want the Catholic opinion on the Sacrament of Penance (confession) and Justification read this articles which explain them way better than me.
newadvent.org/cathen/08573a.htm
newadvent.org/cathen/11618c.htm
On the virtue of Penance
newadvent.org/cathen/11618b.htm

If you want an explanation, fine, but don't interject things like "What frees us from the eternal consequence of sin is the Eucharist" which is heresy according to Catholic teaching. But I'll still reply to your points, if you want…
I never said anything about an "abode". I'm talking about the general reward for our good works. Saints, according to Catholic teaching, enjoy different levels of merit and joy in heaven depending on how much good works they performed during their earthly life. And we can't "lose" and indulgence since it is not something that is stored, but rather a diminishment of the temporal consequence of sins committed in the past.
Christ paid the ETERNAL debt. If I steal 100$, does Christ give back the 100$ to the person? No, it's my job to pay that debt.
Well, that's flat out wrong, on both the eternal and temporal level. We won't be forgiven by God without penance, period. I'm not sure what the EOC teaches, but the Catholic Church teaches that penance is necessary for reconciliation. In fact, it is one of three essential part to the sacrament of reconciliation (aka confession).
Again, heresy. The Eucharist does not reconcile us with God. Baptism/Confession does. The Eucharist must only be received in a state of grace (i.e. when we are reconciled with God), The Eucharist's goal is to free us from the consequence or sin (i.e. the inclination to sin again, the healing/perfection of our soul, etc.).
We must be free from the eternal consequence of sin if we want God to free us from the temporal consequence. If you're damned, there's no point in asking God for less time in purgatory if you're not going there to begin with.
Well prots accuse our sacraments of being check boxes too, yet that doesn't invalidate them. The point of indulgences is to get US to pray, fast and give alms.