Advice on Spain itinerary

To explore Andalucia, I would have flown into an airport there or in Madrid, because now you have a somewhat cumbersome travel loop to plan. But, it's possible, just write it out day by day to see what works for you. Something like this:
train to Cordoba (1-2) {You'll pass through Madrid}
Sevilla (3-4)
return to Madrid (1-3), head to BCN on the 11th
You'll have to drop something--I put the minimum nights I'd consider in parentheses. I only included the "musts" from your list but did not think Ronda was going to work.
This is why I would instead explore places close to BCN if the airfare is set.

Yeah, not a great deal of time, you have basically 8 nights and four stops, but as long as you accept that your are just scratching the surface, then you can do it. I agree with the other poster, flying into somewhere else might have made sense, Madrid the most likely, but that may be water under the bridge.

One big plus or negative is that starting May 6th (lasting until the 11th) is the Feria in Seville, interesting for many, but rooms can be tough to come by and things will be crowded. Either schedule to avoid or take part in. You can do that by heading straight to Seville first, or by doing Madrid first.

A possible route might be train directly to Seville upon landing, about 6 hours. Do two nights in Seville, then bus to Ronda. One night could suffice in Ronda if you get there early, many day trip, and the views are really the attraction. From Ronda, there is a train to Santa Ana, where you can catch the trains to Cordoba, I suggest two nights there, then onto Madrid, where you could spend 3 nights, getting you back to Barcelona on the 11th. Skip Malaga, Cadiz, and Gibraltar this trip.

Have you made your airline reservations yet? If so, why are you flying into and out of Barcelona? If not, you should really fly into Madrid. Unfortunately, you are wasting time flying in/out of Barcelona so I hope you can change your flights if they are already made.

Looks like you have about 8 nights on the ground. Not a lot of time. The following is a possibility:

Seville - 4 nights
Cordoba - 2 nights
Madrid - 2 nights

Logistically, Madrid makes more sense. From our airport however, it was more expensive by $1000CAD, longer layovers, and return flights were better for us from Barcelona. It is too bad, but we will make the most of it! I really appreciate all the feedback, especially the heads up on the festival in Seville/the info to Ronda. The post by Paul hit the nail on the head...we accept that we are just scratching the surface. Thanks!

Plenty of beautiful places around Barcelona, but we all have our own calculus for time/money/travel. Enjoy!

All good.

Would you consider renting a car and exploring the Costa Brava and inland Catalunya?

If not, agree with Val, above, and others, but you are looking at possible sold-out hotels and high prices if it's Feria in Sevilla. You might have to leave out Sevilla, which kind of takes the heart out of the Andalucia portion. But you could still go to Cordoba and Ronda. And spend a couple of nights in Madrid....

Or, stop in Zaragoza and then continue to Madrid; stay in the city and take day trips to Segovia, Toledo, etc.

I think you need to find out whether or not you can get a suitable hotel in Sevilla before you proceed much further.

But again, so many options: if you want to see Cordoba and Cadiz, you could add Jerez and you have the plan right there....all by train. I would NOT include Gibraltar.

Have you seen Maribel's Guide to the Sherry Triangle??
And her guide to Andalucia?