Yes there is another Cardinal Fratelli novella in the works. Here is a quick summary:
The Cardinal and The Constable
Cardinal Fratelli’s misadventures continue in this third comedy novella. Things seem to settle down, Michele and Ernesto grow into family life and an old friend comes from London to visit. However, just when everything seems peaceful, a murder is committed in the city of Lucca- with one of Fratelli’s priests as a suspect!
As his friend seems to have become a totally different person since he knew him, Cardinal Fratelli must help his brother, who is the city’s constable, catch the real killer. All this while dealing with life’s little unexpected turns and keeping his dignity intact.