User could set styles of bold when they use string.
but if there aren't font faces according to the bold styles.
Font weight styles don't work properly.
I just tested it with sample text mentioned below.
and you can also find out the result.
<font=Sans:style=Regular>Sans Regular / </font><font=Sans:style=Bold>Sans Bold / </font><font=Sans:style=ExtraBold>Sans ExtraBold</font>
As so far, efl uses a certain Freetype api which embolden a glyph with singular value of "some reasonable strength".
if fontconfig couldn't find the proper font.
I think efl need to change a strength of emboldening by reasonable value when user sets styles of bold,
even if there aren't font faces according to the bold styles.