MBD Annotations text_thickness depending on text_height

Hi everyone

On the way of defining our method for MBD, I'm adjusting our model properties file.
Now I'm looking for a way to make the text_thickness depending on the text_height and on the type of thickness as Bold.
So far I can drive the text_thickness by a fixed value, but this is not what I prefer. In a zoomed in situation in 3D model even a small  value might be too fat, and the thickness cannot be adjusted for every zooming view separately.

I'm looking for something which works as the thickness type "Bold" or "not Bold" and which stays in relation to the text_height.

Does anybody have a hint?

Thank's for help!