I wanted to add here that a Hired Diplomat will be able to remove the Hostility Penalty (as applied by a law) if Hostility is less than 75. The hostility penalty will be re-applied (automatically) at update if applicable. In this way, players will be able to buy some time till they can sort out the problem (debt in this case).

There is also a strong possibility that in the future, some law hostility penalties might only get removed with this card.

Any chance hired diplomat can be changed to use on oneself? Also, as king of a nation , I would find it very useful to have a page that shows my citizen's hostility with its own nation. Is that something possible?

It is possible. We will add that and also outstanding loans tables.

Hired Diplomat should remain non-self as it would become too easy otherwise. It also helps in providing motivation for cooperation with other players.