Topic Title

Is there a hatch pattern for fiberglass insulation that could be used in tapered conditions?

Writing that hatch pattern would be next to impossible. Even a custom linetype would be a lot of work. I'd suggest a symbol or a series of "stepped" batt insulation linetypes, like what was suggested on the other thread.

As Neil indicated that's a hard one. I have seen people use a pattern like cement (ranodm dots) and just define the boundry to be tapered.
Depending on how and where you are using it, and which codes you are complying with, the current energy codes require that attic insulation be uniform over the complete conditioned space, so taper might not compply.