for now, barcelona is one of the clubs with the best squad in the world so if they intend to buy players again, it's just a waste. What Xavi has to do right now is focus on making the current squad work very effectively. they must be able to at least win a domestic trophy in the following season and the UCL is one of the trophies that Barcelona must target.
Lol, are you kidding me, just by winning the La Liga and Super Cup trophies you gave Barcelona the title as one of the clubs with the best squad in the world. Compared to the quality of Manchester City squad, Barcelona squad is still far behind. Xavi has just lost Alba and Busquets in his squad, it will be impossible for Barcelona not to be looking for replacements when the transfer window opens. So far Barcelona have agreed verbally with Gundogan, Joshua Kimmich is also on Barcelona's radar.
Even though Barcelona won two trophies this season, the current squad is still far from perfect. How can you say Barcelona is one of the clubs with the best squad in the world, whereas some time ago they failed to get out of the Champions League group phase.
Barcelona is not the best team in the world at the moment, even in the previous season they did not deserve this title either.
As an illustration, as you said, the Champions League, which is the league for the top teams, Barcelona cannot get a good position there and is still below Manchester City.
The two trophies owned by Barcelona cannot be used as a guarantee that they are the best team.