I have this cube with skewed faces:
Forces the edge loop to match the shape of the adjacent edge loop. You can flip to the opposite vertex using F. Use Alt+Wheel to change the control edge.
However what I get is that selected edge becomes mirrored along vertical (in this case Z) axis and that's how it's slided:
Choosing control edge doesn't change that, control edge is selected correctly but it's just mirrored.
In the second part of the gif I enable Flip option of the Edge Slide to choose the unselected face as one the selected will match. It works as expected - the selected and edited face gets orientation of that face. It doesn't for the selected face.
Things like scale+rotation are applied and normals oriented outside.
Why does Edge Slide tool mirror the edge it is sliding?