found that removing tar paper is almost impossible. As you know you do need a stable sub flooring for your new tile and one that is even.
With the top layer coming off nicely, but in some cases the 57 tile is coming up also, you now have an uneven surface that you have to contend with.
your options here are to float out the areas where the 57 tile came up and make it even with the entire 57 tile job after the top vino is removed. But then you have areas where 57 tile is not stable and would not work as a sub flooring material. Right?????
Removing the tar paper is in my opinion out of the equations completely.
I have found out that just adding a new plywood flooring as a sub floor is sometimes more practical and feasible. You do have to determine what you will do to bridge the higher level flooring with the not as high flooring transition area.