I'm sorry but this post just doesn't make sense to me. Maybe I'm measuring from a different place on the rig or something. So here's my thinking.
Your marker says from the surface of the water to the bottom is 2.05m
So this means from the bottom of your float (surface of water) your bait would have to travel 2.05 depth to hit bottom.
However you add a 20cm leader on, which means you now have 20cm of leader between the bottom of your float (surface of water) to your bait.
Which means your bait is now hanging from the bottom of the float down into the water 20cm.
Which means your bait no longer has to travel 2.05m to hit bottom.
Since your bait is now hanging down in the water 20cm, your bait would have to travel 2.05m (depth) - 20cm (leader length) = 1.85m for the bait to touch the bottom.
You state you want the leader to lay on the bottom as well. So for the leader to lay on the bottom we would add the leader length back in, which is 1.85m + 20cm = 2.05m not 2.25m.
So from the way you are explaining it, by adding in the leader length to the 2.05m to make a depth of 2.25m you would have the bait on bottom, the leader on bottom, with an extra 20cm of regular line laying on the bottom as well. Is this correct?
The only way I see the original post working like it's explained is if the bait is still seen as starting at the surface of the water, even though it has a leader on.