If you're talking about "Strange apparatus", They're used in a mini-quest to get items like the Arcane Flower pot, Rune Weapons, Cermet, and Crystal Clusters.
Decoration i think :X, some of them have prisoners inside.And I'm also curious as to the san'dorian dungeons cell doors what when you clicked they read "locked"
Gusgen? If i recall it was explained during the Bastok quests.Also I'm curious as to the mystary of Gusgen mines. That is the only zone with cgi specters. And ghost imagry. I have yet seen the zone it is entirety as the deeper you go the creepier it gets.
It used to be a heavy Mining area for Bastok, However on one day, it was something along the lines of "Visit your parents" Day, where the children came to the mines to see their dads in work. Then a fiend cause a colossal cave-in throughout the mines which trapped/killed everyone inside. The ~8 NM ghosts are named after Workers and the way in which they died, the spirits you see floating around are the Miners and their Children's ghosts.
The NM that caused it was Juggler Hecatomb, it spawns every ~21/24 In the basement. If you notice when you go to the basement, theres actually a gigantic hole in the ceiling (Which you can drop down from above right onto the NM), This is how he caused the tremors/cave-in.