As the title says: Setting a BP Amp or Time macro to Velocity or Aftertouch (and an appropriate scale and breakpoint position) does not have any effect to the envelope. All "real" MIDI control changes do.
I did an experiment for clarification and created a patch with Absynth 5 including a pitch envelope where I have the "sustain" breakpoint (set to a medium level) controlled by an Amp Macro: Velocity/Amp Scale: 100, and it works. I then saved the patch and imported it to Absynth 6. With this imported patch, the velocity control of the breakpoint also works! In the "Assign" page I see an entry for Velocity, named "Env BP Amp: Oscil A Main Pitch", but looking at the Envelope page, I find the Amp Macro field for the breakpoint empty (but the Amp Scale displays correctly). When I open the "Amp Macro" pop-up-menu, velocity is checked, but when I re-select it, it stops working (but "Velocity" is displayed again in the Amp Macro field), and the entry in the Assign page/Velocity disappears.
So it seems data from MIDI sources not being MIDI CC are not assigned correctly somewhere, or selecting them as a BP Macro doesn't create the right connection internally.
BTW (off topic) "Note Value/Pitch" (also not a MIDI CC) as an additional modulation source would be nice…