Thanks for your answer.
In the regard of z88. Z88 is only of interest if you explizit know Z88, if not use ccx (Calculix). Z88 was implemented just to have a second solver to get rid of all solverdependend code. Lot's of constraints are only supported by ccx. If you would give z88 a try you need to get the binary from https://github.com/LSCAD/Z88OS/tree/master/bin/mac (you only need the z88r binary)