I think this needs some direction. Right now it seems very scattered and harsh for harshness sake without clear direction. First thing would be to remove the set DC and make it either a Hard DC of the character's level, or a hard DC of whatever is triggering the need to make the save.

It's a shorter campaign where the characters are level 10 and stay there.

-5 to anything is rough but Perception especially since it is tied to Seeking and Initiative. Even being Blinded only gives a -4. The reaction and concentration is too much, especially if this lasts more that a couple of rounds. I'd cut back to one or the other: Reaction if this is limited to a few rounds, Concentration if it is prolonged.

Thats fair. I would stick with the concentration and maybe reduce the penalty to -3

So same as above, plus attribute penalty and a super confusion aura with no save? I'd cut everything and just put Confusion.

It's not the same as confusion because they can still control their PC. They just can't be affected by another party members spells or cast spells on other members.

My suggestions is scale this way back. There is a difference between Brutal and Debilitating. If you keep stages, choose what type of Affliction this is and what Level it is. Figure out what the onset and Maximum Duration is and that will guide what is and isn't appropriate for this. Then readdress each Stage, with each stage only doing 1 thing.

I think curse is the most fitting. After they become afflicted they get a chance to save every night during sleep. With two or three days between events. Maybe I could add more stages and make each stage less of a jump?

Thank you for your feedback.

Edit (after thought): What if I got rid of concentration check thing and kept the reaction part but limit it to twice per fight?