What plants would compliment a Fire Light hydrangea? They would be planted in front of the hydrangea and would be facing east with morning sun and afternoon shade in zone 4.
This article has a nice list of zone 4 plants that tolerate varying degrees of shade:
https://www.gardeningknowhow.com/garden-how-to/gardening-by-zone/zone-4/zone-4-shade-loving-plants.htm