When copying from the Editor and pasting in Word (keep source formatting), basic stuff like font and font size are not kept.

The text will always become Times New Roman, and the font sizes are not the same, for example 14pt becomes 13.5pt...

Using IFrame-mode and injecting css to set default fonts since that is not supported in a proper way...

From what I can see you need to intercept the copy-event and fix the html like your competitors do (for example syncfusion)...