Bayer Leverkusen will try to get a fourth position at least because it will definitely make them qualified for UEFA Champions League next season and they will not have to care about rank of Bundesliga compares to other big leagues in Europe. Otherwise, if they failed to get a fourth position, they will have another chance, getting a fifth position that they currently have, and hope that Bundesliga will finish this season well enough so that the league will be given 5 spots for UEFA Champions League 2026 - 2027.
The second scenario is quite risky and surely Bayer Leverkusen will try to get in top four as it is a safe target, and by aiming at top four, they will also increase their chance of finishing with a fifth position at least.

By the way, yes, it seems there's still a mathematical chance that Germany will overtake Spain and secure a fifth direct Champions League spot. I showed the current league rankings above. I'm too lazy to check the scoring rules, but it seems like Germany's chances are purely hypothetical. Even if Bayern wins the Champions League, the points that the Spanish clubs have (and which they will still earn, including in games between themselves, haha) will be enough to maintain the status quo.
Well considering Bayern may continue, that means that Bayern could win the whole thing and that would make it sort of possible. Doesn't mean that it would be easy, all Spanish teams needs to be eliminated in the next round or this round, and then Bayern has to win, which would be a rare thing to see, not because Bayern may not win, but because we need to see zero Spanish teams from forward here, and Atleitc is already at semi finals, even if they lose that, they are going to get some for being at semi finals.
In the end, in theory it's not "impossible", but it's as close to it as possible, and not going to happen. However, that doesn't mean that it will never happen, if Bayern continues to be consistent like this, there is a possibility.