Questions about sill plate, vapor barrier and soil radon

[Rödgul]

Hello.

In the attached image, you see my sill under a patio door. The sill is impregnated with age-resistant plastic underneath with an upturn. From the sill towards the concrete floor, there is a gap where either polystyrene or mineral wool has been pressed down in different places. This is how it's constructed around the entire house.

The walls are as follows: Exterior wall, air gap a few mm, wind barrier, 120mm insulation, vapor barrier that joins down under the sill, interior walls. The vapor barrier currently there is anything but tight up in the walls.
The floor is a platon system directly on the concrete slab.

So my question is how I can best avoid risking making the sill moist.

Should I change anything?
Polystyrene or mineral wool between the floor and sill?
If I make the vapor barrier completely tight, is there a risk of complications from that?

There might be a risk of ground radon in my area. Should the "gap" between the sill and the concrete floor inside the wall be sealed under the polystyrene/insulation? If so, with what?

Grateful for help.