I think Erik ten Hag should not be one of the important candidates because we all remember what he did with Manchester United. We saw that Manchester United did not perform enough during this period and moved away from the old strong team image. If Leipzig trusts him, they should do much more research. If his tactical touches are suitable for the German league, of course they can bring him to the team, but I think they should also consider alternative options.
I don't have anything against him he might actually serve better, since the league is totally different from premier league, I understand what you are saying ten have not done anything that have earned him merit to be able to be accepted with doubt, but just because of that past record people are really not ready to accept ten, because till now Manchester United are not doing great and they still have not gotten a coach that can put things in place for them.
Leipzig Might have made there choice about him and if they feel they want to give him a chance then they should go ahead, because when they brought kompany a lot of people were very unsure about him, and kompany have proving him self and no one is saying shit about him any longer so the same might go for ten and they might actually have a bad idea about him but everyone deserves the opportunity, he might be bad there does not mean that he will not perform well when it gets to Leipzig. What ever choice they make they have there reasons and to be honest coaching is actually not easy the way people think.