The thing about doing old content is that you cannot do it at its intended level (most of the times). Due to the nature of the game, the best solution is to leave those on your quest log, continue on to Zandalar and level to 120. Once you are maxed, you can go back and finish your hall if you want, because you will be able to go directly to the dungeons/raids entrances and solo the content for the most part. Just how old content works unfortunately.