Per HMV Japan "the Charisma Recordings". My Japanese is non existent, so more than that I know not!
http://www.hmv.co.jp/artist_Steve-H..._Premonitions-The-Charisma-Recordings_6456783
That would mean the box should cover these albums (and more!):
"Voyage of the Acolyte" (1975)
"Please Don't Touch" (1978)
"Spectral Mornings" (1979)
"Defector" (1980)
"Cured" (1981)
"Highly Strung" (1983)
Now we know via Steven Wilson's Facebook page that "Spectral Mornings" has definitely been remixed in surround and stereo, but he said there's at least one other Charisma that was also remixed.
Guess we'll have to wait for further information on this set!