In the climb below area of the grand fissure, casting spells summoned magic eaters.
This is not a bug, the nature of that particular plane includes magic eaters (it is very similar to old UD). However, it may be a bug that the frequency is too high - I recall this happening in v4 after EE when frequency was too high for whatever reason. It is likely that the fix made then did not get put into v5.
Wild animals (like prowlers) and vermins(bugs) - not hostile to characters.
Wild Cave Prowler fixed.
Please be more specific about exact names of which vermin monsters need faction adjustment.