Don’t know what you mean with "outline still persists".
The filter uses only the outline from the background layer. So you can tweak the outline in the background to get the best hatch and rerun the filter. You don’t need use undo or copy the glyph all the time.
The hatched outline as it comes from the filter will not export as open paths are not possible in OpenType fonts. You need to do something with it. Maybe you copy the hatch to Illustrator or apply "change Weight".