The Silver Swan

The third book (you note I'm not necessarily saying "final") in the Swashbuckler series is out now.
Here's the blurb:

In her spacious new home overlooking the sea, Lily is having trouble coping with life ashore.

Parental discipline is boring after months of a carefree pirate life, and it’s not easy to adjust to being back with her family. Everyone is grumpy and on edge, nothing she does is right, and nobody seems to believe Lily's stories of her days as a pirate.

Then one night a fiery family argument is interrupted by a sinister knock on the door.

The world around them has erupted into war, and this time the Swann family goes into action together, as Lily faces her most dangerous adventure yet.