Many books by Abigail Reynolds are available in translation. Here is a partial list of them:

French:

Avec ou sans Mr Darcy? (What Would Mr. Darcy Do?)
La conquête de Mr Darcy (To Conquer Mr. Darcy)
Elizabeth Darcy (Mr. Fitzwilliam Darcy: The Last Man in the World)

German:

Mr. Darcys feine Verwandtschaft (Mr. Darcy’s Noble Connections)
Allein mit Mr. Darcy (Alone with Mr. Darcy)
Die Darcys von Derbyshire (The Darcys of Derbyshire)
Die Kraft des Instinkts (By Force of Instinct)

Italian:

La Lettera di Mr. Darcy (Mr. Darcy’s Letter)
I Parenti Nobili di Mr. Darcy (Mr. Darcy’s Noble Connections)
I Darcy del Derbyshire (The Darcys of Derbyshire)
Il Rifugio di Mr. Darcy: Mr. Darcy’s Refuge
Coming Soon: By Force of Instinct

Portuguese:

O Refúgio do Sr. Darcy (Mr. Darcy’s Refuge)
Os Darcys de Derbyshire (The Darcys of Derbyshire)

Spanish:

Los Ilustres Vínculos del Sr. Darcy (Mr. Darcy’s Noble Connections)
El Refugio De Darcy (Mr. Darcy’s Refuge)
A Solas con el Sr. Darcy (Alone with Mr. Darcy)
Por la Fuerza del Instinto (By Force of Instinct)
Los Darcy de Derbyshire (The Darcys of Derbyshire)