Simply put, in OB 2.3.2 tetrahedral and cis/trans stereo can be roundtripped through a 0D Mol file by using an extension to the defacto standard, as follows:
obabel -:"I/C=C/C[C@](F)(Br)Cl" -omol | obabel -imol -osmi I/C=C/C[C@](F)(Br)Cl
With the current release, cis/trans stereo is only preserved if you generate 2D coordinates ("--gen2D") although tet stereo can be read from the chiral flags for 0D files if you specify "-as".
How does the extension work? Well, for tet stereo it just uses the chiral flags (in defiance of the spec which says to ignore chiral flags on reading - take that spec!!). For cis/trans stereo it uses Up/Down markings equivalent to those used by SMILES; all of the (at most) 4 stereobonds are given Up/Down markings; if two bonds at either end are both Up or both Down this implies cis.
A better way to do it would have been to use a double bond flag equivalent to the chiral flag - e.g. 1 means that the first two bonds that appear in the bond section are cis - this would be both easier to compute and to interpret; however it would push the spec a bit too far.