Complex sentence: It reconstituted itself as a State Council and, without any formal referendum or election, in March 1992 appointed Gamsakhurdia's old rival Eduard Shevardnadze as chairman, who then ruled as "de facto" president until the formal restoration of the presidency in November 1995.
Split into simpler sentences: It reconstituted itself as a State Council and appointed Gamsakhurdia's old rival Eduard Shevardnadze as chairman in March 1992. He ruled as "de facto" president until the formal restoration of the presidency in November 1995.