Hey Gunter,
I can look at your file later. But from your screenshot, let me say this.

First, you wont be able to taoer extrude to a single point (its a limitation)

But you don't want to either.

In your image you have your drawn tool sitting all the way down in the text geometry. At full depth. And it looks lile you are wantimg to extrude the text "DOWN"...

You want to move the tool UP in that file, untill the tip is at the depth you want. Then, taper extrude the text UP untill the side walls intersect or clash with the tool. This is what will limit the depth of the tool.

Then you delete the original text and use that new top face of the tapered extruded text to vcarve. When the tooling is constrained by the new, offset text edges, the depth will be shallower.

Not sure about the flat bottom. I saw it mentioned that vectric has this option. Be sure you untick that option.