Some of the decorative stitching has some reverse stitching in them. It is built into the stitch. Take a scrap piece of light colored fabric, put in some dark thread and do a sample. With the stitches that go backwards make sure that you don't hold the fabric so tight that it won't go backwards freely. It is weird when your fabric moves forward a couple stitches then automatically goes backwards a couple stitches.
Foolish question---when you have your machine go in reverse do you stop and disengage the accufeed? If not why wouldn't it work with the built in stitches? Their problem probably was holding the fabric to tight and the fabric couldn't freely move backwards to make the correct stitch. I have a Pfaff that has the original IDT system and it is made to go forward and backwards.
Good luck and have fun!