Casadó, 21, has fallen out of Hansi Flick's plans and has not featured in a matchday squad this season, with the head coach preferring Frenkie de Jong and Marc Bernal in central midfield.
Real Betis are working against the clock to find the necessary wage-bill space, with the futures of Nelson Deossa and Álvaro Fidalgo both still unresolved, before they can meet Barcelona's asking price. According to Marca, Barcelona are prioritising an outright sale worth around €30m while retaining a sell-on percentage, whereas Betis would prefer a loan with an option to buy — a structural gap that leaves the deal far from close with hours remaining before Tuesday's deadline.
Bayer Leverkusen have also shown interest, giving Casadó an alternative route out of the Camp Nou.
Should Betis clear the necessary space, coach Manuel Pellegrini would also look to complete the signing of Dani Ceballos, whose return to the club where he came through the academy is edging closer. Betis need both deals to work in tandem with their exits, since their available wage-bill margin under LaLiga's spending rules cannot currently stretch to accommodate both.
Elsewhere in Barcelona's academy business, midfielder Guille Fernández is set to leave the club on a permanent transfer to Mallorca. According to SPORT, the Balearic club — recently relegated to Segunda División and aiming for an immediate return — have moved decisively in the deal's closing stages, with Barcelona retaining a percentage of any future sale.
The 17-year-old, regarded as one of La Masia's leading prospects and represented by Jorge Mendes, had been training away from the first-team group for several weeks awaiting a resolution, alongside fellow fringe players including Casadó, Héctor Fort, Tommy Marqués and Jofre Torrents. He is expected to link up with head coach Luis García and former Barcelona team-mate Pablo Torre in Palma.
Barça Atlètic, meanwhile, are pushing to complete the signing of Betis centre-back Jean Emmanuel N'Goran as they build a squad capable of challenging for promotion back to Primera Federación. According to journalist Ángel García, competition is coming from Rayo Vallecano, who can offer the 19-year-old a more direct route to first-team football.
N'Goran, who progressed through Betis's academy after arriving from Ghanaian side Young Africa, has previously been watched by Chelsea and Manchester United and already has experience against Barcelona having scored past their youth side in a cup tie. He would join a rebuilt Atlètic squad that already includes summer arrivals such as Joni Hernández, Juan Ybarra and Mirza Catovic.