The easy way we fixed it when we still played dnd is that casters know what the spells are, even if it's not in their spell list. You know if the enemy is casting firebolt or finger of death. Consider that if it's possible to counterspell counterspell, which only has somatic casting components, then probably there is sufficient time to tell what each spell is. This fixes the bad feel of counterspelling because the spell is known by having everyone do it. Everyone knows what the spells are so you can choose to be strategic and get the most out of your counterspell.
If you want to justify it, you can imagine that all fire spells have some fire movement or incantation, add to that something related to size or expansion, plus a bead of fire forming, that's a spicy fireball.