Frankfurt would be happy if the current ranking is the final ranking of the season. They have unprecedented successes there for a club that has not achieved much in recent years. And financially they will also be well off. You also have a lot of television money in Germany, so it is not only attractive from a sporting point of view to finish high. The higher you finish, the more interest you will have in the television money that will then be distributed.
As far as I know club income from TV rights is significant only in the Premier League. Therefore, Frankfurt would be happy to remain in their current position only because 4th place provides a direct ticket to the Champions League where the club's income is significant. But it will be difficult for them to hold this position as Dortmund are behind, plus Union Berlin will probably get back in business and play well again.
True, the fact that the difference between the bundesliga and the EPL is very big is definitely felt so it will be very good for Frankfurt to be in that zone because indeed this will definitely lift them up financially.
Their condition last season to get the Europa League was very good. on the other hand, currently entering the knock out phase at champions lageue, they will definitely get more benefits from that, so indeed their steps to get more financial now are certain they want to continue to be in the top 4 so they don't lose the bonus from being in the champions leagues.