I've been working on a combat overhaul that
has this feature for a while now; stay tuned :)
Yes!
Please provide me with a crashlog as well as the
things happening when the crash occurred, this
will greatly help me debug.
Zxlice's parry is done differently.
It does not cancel the light bash hitframe.
The parry can be triggered by landing a bash
on an attacking enemy at any time during their
attacking animation.
IMO, this makes parrying way too easy
and bashing only more overpowered.
In addition, Zxlice's parry is made only for melee
attacks while Elden Parry works for projectiles too.
I wouldn't suggest enabling Zxlice's parry
due to its overlapping functionality.
However, you can keep its backstab by
turning the parrying option off in its MCM.