There is no danger and no work on the pre-tensioner system.
Mostly, the belt is twisted behind the B-pillar!
It must look like image 1! The belt must be twisted 180 degrees in the visible area. If it is NOT twisted from the B-pillar to the mounting point beside the seat, then it is (wrongly) twisted behind/insind the B-pillar.
So you only need to remove the cover (by first removing the A-pillar cover, then the C-pillar cover, after that the B-pillar cover can be pulled out
) and then you can fix it by twisting it back so it is right and not twisted inside the pillar.
It should look like image 1.
Image 2 shows how it is wrong. There you see the belt is twisted inside the pillar. This may not be.
Image 2 shows also the round metal stripe where the belt goes behind. You can oil this by using Silikon oil. Or just spray it in!
Use the silicon oil, then the belt will retract better The oil also can be used without removing any cover/trim.
But first make sure it is only twisted 180° on the out side.