There is a Workbench plugin for SE but as I found out a while ago, it doesn't support the SE frame tool. You can export the model to .xt and frames will show up but from my perpesctive that defeated the point.
Theodore I think it is something to do with the way SE uses a wire frame to define the path. I'm guessing the geometry doesn't exist in the same way other solids do within the model. This isn't the first time I've encountered this issue. Bunkspeed renderer can import native SE files but again, frames don't work, so I think it is safe to assume it is on the SE side. SW doesn't seem to suffer from the same issue but I think it handles frames in a different way.
I raised the issue with Grabcad at the time (they were keen for paid subscriptions at the time so kept phoning me) but they had no solution. The stark reality is that SE simply doesn't have sufficient market penetration to make partner programmes work. Roger