The only way to fix it would be to create a custom recipe(similar to the composite lens recipe) that sets the tag properly on any lens, not just on particular metadata values.

I know.

Bit late to the party here (I only just found this issue tracker), but I may have a workaround: instead of properly fixing it, allow the player to separate the compound lenses in the crafting grid (the slimeball would be lost). That way, the player can re-tint the top lens, then re-combine them.