How to avoid dividing editable text written in one line into 3 parts when saving in EPS 10 format?

Question

Fonts

Is it really impossible to write Regular and Semibold in one line?
Empirically, we also managed to find out that splitting occurs not only when using different font styles "Regular" "Semibold" but also when using different colors in one line of text.
I want to get a whole line using different font styles and different colors when saving the text in eps 10 format, tell me is it real?