I would think the first question to ask is whether the source model includes data fields representing spacing and cover
I had tried this on many BIM software which provides rebars facility.
Data is entered in that software, but nothing is exported to IFC , as till mine study i did’t found any attribute given by BuildingSmart which stores values like spacing between bars and cover etc.
So First job is of BuildingSmart to define particular attribute and syntax of it,
Then only software vendors will implement it .
Thank you