Double rod mesh including privacy screen on L-stones! Feasible?

Opaque curtains? Pleated blinds? You’re not building a fence and then removing it again later.

How far is the L-block wall from the property boundary to the street? I see the following problem: There is no space in front of the L-blocks for a proper foundation. Even if you ignore the boundary underground, as you yourself write, you need a 4m post at the "high end." That also has corresponding leverage, and strictly speaking, you would need an even larger foundation, or the post might not be thick enough. That's why my suggestion is to go behind the L-blocks and embed the anchors in concrete. At the "high end," you can make it the usual 80cm deep (and theoretically even embed the posts there). Later, just shallower but longer and wider. At the very front, you might even be able to remove the L-blocks again and pour a deep foundation under them, then connect everything together with long screw anchors (glued in). That would be the super secure version for the paranoid. I would probably just screw the last posts onto shallower concrete bases (alternatively concrete block steps). That would weigh around 100-150kg. If the rest of the fence is properly founded, it will hold because it is connected.

Or does there have to be some distance there?

So that the good L-stone is not spoiled by the bad influence of the mixed concrete? Segregation is unnecessary in my opinion. Paranoid people can leave an expansion joint.