About Soma Bringer, there is an English patch for this game :
Well I do not have many skills for drawing, and I do not pretend to know all is in the mind of Soraya Saga (aka Kaori Tanaka).
However I suppose what will probably please her would be a work based on a doujin she wrote after the release of FF VI :
To resumate, this doujin explains all the background elements about Edgar & Sabin that couldn't be inserted in the game itself. They are (globally) very interesting. The doujin deals also with other main characters of FF VI.
The doujin is of course in Japanese, but some partial translations are scattered on the net.
I put together some stuff here :
Remember : some names are different in Japanese (Sabin = Mash).
I heard she also wrote a very good doujin of Xenogears, but I couldn't find anything about this.
As for Xenosaga, it is probably not a good idea to even mention the name of "Xenosaga" : too much bad memories for her.
Anyway I want to say that you have all my support (and my knowledges of FF VI) in this project !
P.S. 1 : here is a picture drawn by S. Saga herself (just guess who is on it) :