This is by no means a complete answer, but the first two tools that came to mind in supporting discovery were 1) Curiosity and 2) Boundaries.
The boundaries create the container for magic that Susan has described. Setting aside time for practice, defining the practice, defining our role as a meditation teacher – this is the very container for discovery. Without boundaries, we end up with issues like codependence, enmeshment, and transference. Instead of supporting a person’s process of discovery, they may feel dependent on us to have insights and epiphanies. This is just one example, but a lack of boundaries can end up being a mess in a whoooooole bunch of ways.
Curiosity leads to depth and expansion of discovery. If we lack curiosity, we have a finite outer limit of what can and cannot be discovered. To quote Vimalakirti: do not impose the narrow path upon those who aspire to the great path. Curiosity from a facilitator allows discoveries to unfold naturally and be deeply explored, instead of narrowly defining where a practice will lead.