Unfortunately, also impossible with the modifier system, so I doubt it.
Speaking of specialists, I really hope they become more important again in Civ 7...They're entirely forgettable in Civ 6.
Yeah, the base version of specialists really are brutal. Your Improved Specialists mod makes them usable, but even with the mod, they're still mostly only useful if you don't have tiles on the map to work, or if you haven't gotten around to improving them. I feel like it's really a missing piece of the game, and arguably would be a fantastic way to simulate "Urbanization" more than anything else.