We enjoyed staying here and would recommend this place to anyone.
Her place is about a 10-15 minute walk from the Santa Justa train station. It's located near some restaurants and shops. If you're planning on exploring Barrio Santa Cruz, the Cathedral, and the Alcazar it's ~15-20 minute walk. The neighborhood was quiet and felt very safe.
We didn't get a chance to meet Carla since she she was on holiday, but that didn't prevent Carla from going out of her way to regularly check-in with us to make sure we got to her place without any problems. She was very responsive during the entire trip and she has a guidebook to Seville prepared for her guests in her apartment.
The whole apartment is kept very clean. Wi-fi is fast, AC works great.