So you have different objects - PointA, PointB, PointC.. And you want to get X coordinate from one of these objects, depending on the value in En1ac.point variable?
The closest solution to what you have in your screenshot would be using ternary operator:
(En1ac.point="A" ? PointA.x : En1ac.point="B" ? PointB.x : PointC.x)
You can also add all these point objects into a family and pick the family instance.