I expected to find that ‘Filter Env’ and ‘Volume Env’ were available as modulation sources in the pot mapping menu… i.e so that I could map the filter env to osc pitch, for that classic zappy bassdrum sound.
“Pot Mapping” sources are all physical controls; the concept of pot mapping is that you can map additional parameters to a physical control such as any panel knob, the pitch and mod wheels, and the keyboard controls (velocity, pressure, pitch CV). This is good for tricks like making the mod wheel control three things at once, or routing velocity directly to output volume or filter cutoff without using a mod bus.
For what you are trying to do, though, you will need to use a modulation bus. The envelope voltage is available as a programmable mod source, along with several other sources which do not appear on the panel.
So, you’ll want to set the Pedal/On bus Source selector switch to Noise/PGM, which selects the programmable modulation source for that bus (noise is the default programmable source). Next, go to the EDIT menu and select “PGM Pedal Source.” Second option on this menu is Filter ENV, which is what you’re looking for. Now the filter envelope is routed to the Pedal Mod Bus, and you can send it to Pitch as your destination, and start programming some drums! Try using the Filt. Env. as a Shaper also, to see if it gets you a steeper slope to your zaps…