A club sometimes has its own goals, for example, Bayern Munich, which last season was overtaken by Leverkusen, but Bayern Munich prioritizes matches in the Champions League, even though they only reached the semi-finals, but that is proof that a club that has lost in the Bundesliga doesn't necessarily look weak like that what you said and I agree with all of this.
Not being able to occupy 1st position in the points table is not a big problem as long as Leverkusen can perform well in the Champions League as I said above and it is very natural that a club like Leverkusen, which managed to win the title last season, is more enthusiastic about being able to win a higher title, but it must giving up a little position in the domestic league.
Leverkusen I am sure that this club can show its strongest performance in the Champions League as long as it doesn't make many changes to the players, but I am a little doubtful that in the future Xabi Alonso will also prioritize the Bundesliga title and in the end its performance in the Champions League will be slightly affected.
I would feel like it would not be really a team that focuses on one thing. This team is a huge club with a lot of deep pockets, so that means they are capable of building a team that should be able to win the league, and the UCL without focusing on just one of them. I think it was 2020 when they won everything, league, cup, UCL, basically everything. That is why I feel like a defensive statement about how they did not focus on the league and just focused on UCL is just a cheap answer.
This season, they should focus on the league and the UCL at the same time, but if it's true that they can focus on just one, then they should focus on the league, because they need to get back to the top, that is the only way to grow better.