Translation:I would really like this to happen.
This is a tip that helps me figure out when to use past subjunctive and when to use present subjunctive:
-If the thing is not real and cannot be, you use the past subjunctive
-If the thing might or might not be real, you use the present subjunctive
This is more helpful than trying to determine which subjunctive to use by basing it off of time period.
I am uncomfortable when DL translates the conjunction "que" as conjunction "if" to enforce the conditional form. Specially when these clauses are not connected by a condition.
"Eu gostaria..." is close to "Eu desejo..." -> "I wish this to happen"
While, the conditional would need an action in the future past, like "Eu ficaria feliz...".
"Eu ficaria realmente feliz se isto acontecesse" = "I would be really happy if this happened"
What do you think?
Your last sentence parallels the English structure.
To talk about wishing for a change of behavior or of a situation, we use wish + would. When using "wish" in this way, you don't really expect change. It's like a complaint or wishful thinking.
• I wish it would stop raining.
• Bill likes to drive faster. I wish he would slow down.
You can't use wish + would with the first person because the change that you want doesn't depend on your actions.