Here is a sample of Valance‘s externally clocked sequencer mode. Its playing a sequence with an RC-type slide.  In the middle of the display I’ve switched from playing in reverse to playing in the forward direction.  Notice that the sequence in reverse is a mirror image of the forward sequence, including the slide shapes which have had their curves inverted.  All of this is is independent of the speed of the sequence.

Here’s the same thing happening with an 8 note sequence.  An inverted RC-type slide is used and the sequence is switched from forward to reverse in the middle of the display.