Sela is amazing. I have stayed at airbnbs all over the world and Sela has been the best host I have ever encountered. She truly cares about your visit to Barcelona and she is super accommodating in your check in and out. My aunt and I had very different departure times and Sela was very understanding.
She is very close to Plaça Catalunya (2 stops in the fgc) so getting to and from the airport is a breeze and she was kind enough to tell us there are elevators all the way (which we appreciated or else we would have taken the stairs).
The apt is on the 4th floor but there is an elevator!!! It is not common to find elevators in Barcelona since the buildings are quite old.
I would definitely want to stay at her place again next time I visit Barcelona (hopefully soon!)