Sadio Mane is just the perfect player to replace Lewandowski, I don't see anything that is too hard in Bayern Munich that he can't adapt to. He is already a solid player, where he is coming from was not an easy place that every regular player can fit in and make a good impact. I don't see anything that will be to hard for Sadio Mane in Bayer Munich that will be beyond his control.
Most likely it will be like this, especially in this case it is clear the Bundesliga is easier for him because there the game is not as fast as in the EPL and indeed this will be good for him at the moment.
For productivity goals indeed in this case there needs to be a little more hard work but for adapting to the team I seem to have seen their cooperation well and Mane's adjustment was very fast.