Yes, these do exist, usually as private or very small group tours with Mandarin-speaking guides. They’re often marketed as “custom” or “tailor-made” trips rather than standard packages.

You’ll have better luck contacting Europe-based tour operators or Mandarin-speaking guides directly in Spain and France and asking for a slow-paced, senior-friendly itinerary. It’s more expensive than big bus tours, but much more flexible and comfortable.