AFAICT, html2bbcode doesn't handle font tags.
The challenge is that the bbcode output depends on an attribute of the font tag:
<font face="arial"> -> [font=arial] <font color="red"> -> [color=red] <font size=2> -> [size=2]
A bigger challenge is that a font tag could have more than one attribute.
If you could add the facility to define a combination of a tag + single attribute -> bbcode in the mapping file, that would be excellent. If there was a way of doing this so that it also handled the tag + multiple attributes, that would be outstanding!