Intercepting higher neighboring plots: L-shaped stones, etc. - Tips

There's basically nothing against that. The only question would be whether they hold just as well as, for example, angle supports?

The advantage of angle supports is that the slope partially supports itself by pressing on the base. Accordingly, you can make them relatively thin, e.g., 10 cm. With a wall, this base is missing. Therefore, you generally have to make the wall somewhat wider, reinforce it, and anchor it well with a foundation in the ground (variant: shuttering blocks). Or you use much larger stones that have a better width-to-height ratio (variant: ashlars). Tilting the wall against the slope also helps but is more suitable for natural stone walls or planting rings; shuttering blocks then look built crooked.

The advantage of retaining walls is that the slope partially supports itself by pressing on the base. Accordingly, you can build them with relatively small thickness, e.g. 10 cm. With a wall, this base is missing. You then generally have to make the wall a bit wider, reinforce it, and anchor it well with a foundation in the ground (formwork block variant). Or you use much larger stones that have a better width-to-height ratio (quader variant). A tilt of the wall against the slope also helps, but that is more for natural stone walls or planting rings; the formwork blocks would look crooked then.

The landscaping contractor mentioned to us that he would make the foundation 1m deep and then build the wall from formwork blocks.

Our idea was to plaster and cover the wall and create a flowerbed in front of it. This way, the wall is as far as possible from the house and a few nice plants also make it more attractive.

I have seen many pictures of this on Pinterest & co.

Edit: the only problem now is that the retaining walls of the neighbors' driveway extend onto my property. Would it have been allowed/possible to build the wall directly against the existing stones? I did not ask the landscaping contractor about that.

The support side of the L stones must not be on your property. Is there a building encumbrance in the land register? Who is the owner of the driveway? Without information about the condition, no assistance can be given here.

The bearing side of the L stones must not be on your property. Is there a construction encumbrance in the land register? Who owns the access road?

Without information about the condition, no help can be given here.

I claim that there is no construction encumbrance in the land register and will check my documents again in this regard.

The access road belongs to the 6 houses (4 owners) in the second row. I will inform them accordingly as soon as I know exactly whether this was allowed.

It could also be that the property boundary runs along the support feet.

It could also be that the property boundary runs along the support feet.

I had looked at that before. The stone itself lies on the driveway property, but the foot of the bracket is on our property.