So far, Xavi is one of the most successful coaches in my opinion. Barcelona doesn't need to act rashly by sacking him and finding a replacement coach for him
Well, Xavi ranks amongst good coaches in europe today; but he does not rank as one of the most successful coaches in europe; and if Barcelona sack the dude today' they will face little difficulty replacing him.
The problem with Barcelona this season has to do with players depth, injury profiles and poor investment in the squad. No coach can fix such deficit.
Better for Barcelona board to trust the process with Xavi
I quite agree with your opinion. because there are several examples that Xavi has experienced, for example coach Kloop at Liverpool, he also took quite a long time to grow Liverpool to what it is today.
Xavi also deserves to be given the opportunity to try to restore Barcelona, especially with Barcelona's financial condition not yet improving. So if they fired Xavi it could be said that this was a careless act, because he deserves to be given a second chance at Barcelona. Barcelona's problems, as you said, are quite numerous, not only Xavi's fault, I'm also sure, even if Xavi is fired now it will not increase Barcelona's self-confidence. Currently, Xavi will of course continue to rise, especially since they have just won the last 16 match of the Copa del Rey with a score of 1-3. However, Barcelona's defeat against Real Madrid in the Spanish Super Cup was no reason for Xavi to defend himself because it was also his mistake in implementing strategy.