Three pressure plates puzzle mystery (spoilers!)

I think I lost an hour yesterday on trying to get this done in several ways, no dice.
Posted it on Steam (someone else also got stuck on it), noone solved it.

Location: Reapers Coast approx coordinates x170, y60

A pic where pressure plates are (location of possessed dwarven ambush).


One pressure plate is by the green ghost, another near Fane (left) and third is all way up. There is no fourth.

Anyone solved it?

I actually think those are pressure plates that cause the barrels near them to explode during that encounter.

Unless they are tied to the statue with a quest on the higher ground near there, but I kinda doubt it.

No, the statue quest above that area is easily solved:

I missed these pressure plates completely! Wish there was possible to go back to the first island - I just have fought the last battle and sailed out…