Bayer Leverkusen can win all the domestic competitions at least. So, they never got a defeat in all domestic matches during this season. It is also a good record, only very limited teams that can do this record. Leverkusen won 2 trophies, it is cool achievement for a new rising team like Leverkusen. It is quite good for them. Congratulations!!

Indeed Bayern Leverkusen tried even though they didn't finish the season in an unbeaten run in all competitions but they did finish the Bundesliga in an unbeaten run so they are the first team to set such a record which can be difficult for any other team to achieve within a short time. The record alone has set them outstanding in the Bundesliga and for them to win the trophy and the DFB Pokal is a huge achievement for them so they shouldn't feel bad that they didn't add the Europa league trophy but if they continue in this performance they can still win European titles in the future.
Yes, definitely. For Leverkusen and other clubs, Leverkusen's achievements this season under Xabi have been truly fantastic. It doesn't need to be in accordance with everything the fans want, because, sometimes this is precisely what can make Leverkusen become much better and stronger in the next season. Although it might be quite difficult to defend the title, because of course Bayern Munich and other clubs are competing closely. However, as long as Xabi is still there and they can get more pro players, Bayer Leverkusen should be able to handle it very well.
Anyway, Bundesliga will add a team to send for the UEFA Conference League due to the victory of Leverkusen in the final DFB Pokal. Congratulations to Heidenheim that finishes in the 8 position and is now officially to UEFA Conference League playoff.
Source: Heidenheim will play in the UEFA Conference League play-offs