He is elected by EP (which is directly elected) and the European Council (members of which are directly or indirectly elected in their countries) so he is only

He is elected by EP (which is directly elected) and the European Council (members of which are directly or indirectly elected in their countries) so he is only twice and thrice removed from the voters, which is the same or closer than most of the actual "bureaucracy" (and that's not a dirty word and voting process in itself is very bureaucratic too) that governs people lives in nations is (which is not a problem or sign of 'deficit of democracy' or whatever to anyone who uses these arguments against the EU). Luxembourg also (article) continues/doubles down it's tax deal policy despite him not being their prime minister anymore so these deals are not bad enough to burn whoever defends them to the point of being unelectable, the commission is now on that case and he as the President of the Commissioner answers to EU structures so if he does prove inadequate in his role and other countries' representatives care enough then he is toast (and if they all don't then who/what is supposed to take care of him and on whose democratic mandate?) but if he doesn't then there is no reason for him to get removed even if Luxembourg hates him for it, support of home country is clearly not formally or practically required, i.e. Tusk stayed where he is (Council President) without Polish support because other country heads kept him there.