Help with itinerary order!

Admittedly, it was many years ago; but the bus from Lisbon went more or less directly to Sevilla. It did not go by way of Madrid. As I recall, that's what you had to do if you wanted to travel by train, not bus.

To reasonably get as much into 15 nights ...

Arrive Barcelona (3N)
Fly to Granada (2N)
Drive to Ronda (1N)
Drive to Seville (3N) - day to Cordoba
Train to Madrid (3N) - day to Toledo
Fly to Lisbon (3N) - day to Sintra
Depart Lisbon

You need to run a cost vs benefit over the Tarifa - Tangiers bit as it really is 3 days total out of your limited time when you account for getting to/from Tarifa.

Morocco is wonderful; Tangier not so much. It is not worth the time it takes on your too-short trip, as David has suggested. You do not have adequate time for Barcelona or Lisbon as it is, or for Madrid if you're an art-lover.

The AVE can make the Barcelona-Madrid run in less than 3 hours. There is no overnight train on that route. What there is, is a connection that has you spending over 7 hours in Zaragoza between midnight and 8 AM. That would be a miserable experience no matter how much money it saved.

The best way I've found to see what's really happening with European trains (but not fares) is to use the Deutsche Bahn website. Select a train, then choose "Show details". If you're interested in the number/timing/location of intermediate stops--as you should be for an overnight trip--choose "Show intermediate stops". All will be revealed.

When you are comparing flight times to train or bus times, take into account all the extra time that flying requires - getting to/from airports outside the city, security checks, possibly time for checking and collecting luggage, since there is often very limited carry-on allowed on the small planes that fly those routes.

Consider flight to Granada, then train or bus to Sevilla, then train to Madrid, then flight to Lisbon. The only alternative I see is train to Madrid, bus or train to Granada, then Sevilla and fly to Lisbon. 5 cities in 14 days is perfect. If you want to add another city, Cordoba or Toledo. Or take day trips from Barcelona and Madrid.

What Rosalyn said.

The train takes at least 13.5 hours overnight and does go through Madrid and back. Check that out on Loco2. I could find only ticket routing to Lisbon that started in Cordoba, meaning (I think) that you'd have to get separate tickets for Sevilla to Cordoba.

The bus is faster at 8.5 hours and travels during the day. You can verify that at the ALSA website.

Edited to add: Have you checked on flights from Barcelona to Granada? Google Flights is showing 1.5 hour Vueling Iberia nonstops from Barcelona to Granada on September 28 ranging in price from $58 to $82. I'd probably do that based on my arrival time plus a big fluffy cushion for the plane being late.

I also checked on flights from Seville to Lisbon. Both the nonstops and the 1-stops (primarily through Madrid) seemed a bit pricey to me. I'd stick with the bus and enjoy the scenery.