It is possible to search books in an specific language adding lang:code to the search string. See for example some searches:
There is other topics than lang that can be used:
The Imperial Library of Trantor has support for OPDS, witch allows you to browse and download books from any ebook reading software that supports OPDS. To use it just add the following url as your catalog address in your device:
For the command line geeks there is a cli client: hummin
To install it in a debian based system (like ubuntu) just do:
$ sudo apt-get install golang $ sudo go get github.com/trantor-library/hummin $ hummin
There is a JSON API for the library, with it you can write bots and other cool things like hummin.
You can add
?fmt=json to almost any page on trantor and you'll get a json of the contents of the page. I'll love to hear if you do something cool with it, please tell me by email.