As posted on FM the Sony and SA flange distances are the wrong way round. To maintain proper function you need a lens from a system with a long flange distance to adapt to a camera from a system with a shorter flange distance so that the adapter makes up the difference. With SA at 44mm and Sony at 18mm the Sony lens would need to be recessed into the SA body by 26mm to maintain function (focusing at infinity).
The Canon EF lens is from a system with a longer flange distance (44mm) but unfortunately it's not going to work as the SA also has a flange distance of 44mm. So there is no space to add an adapter. If the EF lens mount could be removed and replaced with an SA mount it would work. Sigma in fact offer this service for their own lenses but the cost is very high (close to a lens cost as I recall).
This is a good reference to use when considering adopting one lens make to another makers body with an adapter.
https://en.wikipedia.org/wiki/Flange_focal_distanceMike