I'd like to suggest changing the mechanic of Lightning Bolt's arc or the spell's targeting.
Right now, it can hit multiple enemies but this is happens rarely and cant reasonably be timed except in cases where everything is clustered together. In effect it is a single target spell.
Instead, change the 50% chance to arc to a chance to arc on an adjacent enemy of the target within a few yards ( medium humanoid body length perhaps). Limit the number of targets to one or two additional to the primary target. In effect, the spell will only arc on enemies closer to the primary target, so it will hit multiple when there are multiple, while still having the utility of single targeting at a distance.