Well, I'm making faceted and diminished uniform polychora to create non-uniform regular-faced polychora convex and non-convex. And other feature that I need is diminish a vertex and take the convex hull of the others.

Hi, a feature that I want is a 4d off file generator.

Yes.

I want to make partial tetracombs.

Hi, Stella can't recognize 4d symmetry, but you can create an augumentation tool for 4d using:
1) augument selected cell.
2) augument cells of selected type.
3) augument cells with the same shape.