The "special" flag could be set with some script. Text objects start with a "4"
This is a normal text object:
4 0 0 50 0 0 12 0.0000 4 167 425 1225 1588 $a_b$\001
And this is the same with the "special" flag:
4 0 0 50 0 0 12 0.0000 6 167 425 1225 1588 $a_b$\001
The flags encoded into the 9th value with logical OR.
Bit Description
0 Rigid text (text doesn't scale when scaling compound objects)
1 Special text (for LaTeX)
2 PostScript font (otherwise LaTeX font is used)
3 Hidden text
So, Special plus Postscript is Bit 1 and 2, which makes 2+4=6
Color gradients are not supported by the FIG file format. I would like to support them, but I would have to create a new version of the file format. Kind of difficult, because Xfig compatibility is still a requirement I want to keep.