External ass subtitles and fonts

Hi guys,
Is it possible to use the fonts specified in a external ass file instead of the system-wide one?
I'm extracting subs and fonts from 10bit encoded anime episodes (to be used on standard 8bit encoded raws), placing the fonts in the font folder (new fonts do appear in the subtitle setting dropdown), but still the subs get rendered using only the default one, arial.
Is this the expected behaviour or there's a problem here?

Thanks in advance