by the way ...

Where I also have big problems is, to cutout/engrave Typo
on curved surfaces.

In this case I think I have to use "timm"
So what I#M doing is:
1. selecting object
2. select the typo-curve
3. trimm
4. offset - inset or shell
and then ...
5. problem

Should I do this also via "boolean"?

thanks
Mike