As I understand the effect you're after. You might want to look at the HF as an influence mask on another fractal that gives you steep sides and cuts like a billows noise. If there's enough graduation grey in the map, (you could do this in TG with simple shapes), you can then use bias or gain to form the basic shape of your crater. The advantage of doing it this way, it gives you the ability to control the steepness of the sides, therefore giving TG more 'top-down' information on the slope to draw more facets. Once you have your base shape, you could export this into world machine (use a HF generate, right click and save .ter) to erode or form further.