With D:OS and D:OS 2, you can use the EE pak extractor (download) to extract the contents of the localization .pak files.

..\SteamApps\common\Divinity Original Sin Enhanced Edition\Data\Localization
..\SteamApps\common\Divinity Original Sin 2\DefEd\Data\Localization

I'm not sure if there is a way to extract the books for Divinity 2, or if there are any sites that list the books for any of the games.

The development of Fallen Heroes has been put on hold: On the future of Fallen Heroes.