The main issue that Xabi Alonso should seriously address is the defense, which so far hasn't looked very solid. Having a sharp attack is pointless if the defense is porous, it won't lead to success. Therefore, Xabi Alonso must find a solution to encourage Raul Asencio, Dean Huijsen, and Trent Alexander-Arnold to reach their best potential.
Last season was a bad season for Madrid. If I am not mistaken, they had 51 injuries. Only 2 players managed to stay fit until the end, Modric and Guler. According to the doctors' analysis, most of them had muscle injuries. This condition indicates that the players have a very heavy workload. As of now, I do not know about some players who are suffering from long-term injuries, I hope they recover soon. Because Xabi is indeed building a team. He should take advantage of this transfer moment to add a center-back and a central midfielder who are ready to be used.
no Real Madrid defenders are injured except for Bellingham.
So it is likely that Real Madrid's entire defense is now ready, meaning Xabi does not need to worry about starting the league later and they can return to playing the key players they really need.
So far, there has been no news that Real Madrid will add more players to their defense.
Yes, the point is that Real Madrid must learn from all their mistakes from last season. Because it would be pointless for them to bring in new players and a new coach if they cannot learn from their mistakes. So, if in the previous season Real Madrid faced a wave of injuries caused by the intensity of their training or due to overly ambitious targets, then this season Real Madrid must find a solution to that problem. Because it would be pointless if Real Madrid set overly high targets but many of their players are injured. Their targets would certainly not be achieved.
Regarding defenders, I believe Real Madrid does not need to seek new players at this time. The current defensive lineup is already more than sufficient. So the key is how Xabi can turn them into a great team. In a few days, Real Madrid will face WSG Tirol. I believe this will be the only friendly match Real Madrid will play, as their time is severely limited.