Since the game does not currently provide a clear-cut way of knowing for sure what units can trigger bonus lore relation effects with who, I think it could be a helpful thing to add a way to view a unit's Lore Relation list. Maybe somewhere in a Friend Details section or in one of the little buttons on the left of that, or even in the Journal tab instead (or anywhere else that might be a good way to access this), you can access details about which other units will trigger the lore bonus. Some of the Lore Bonuses are easy to figure out (L1 Toyohime and L1 Yorihime), and others (L1 Tojiko and L1 Okina) may seem more obscure to some.
I think this would be a net positive from a lore enjoyer's perspective as well as from a meta standpoint, since it could contribute to forming a strategy to clear or farm a stage, especially in harder stages where switching in and out is more necessary. Stuff like 1.50P instead of 1.00P via Switch Link could make all the difference.