Not a bug: the (badly named) English-only installer means that only the installation program will be in English. But it will still install LimeWire with support for all the available languages.

Then LimeWire starts and uses (by default) the language that matches the one for your local system and/or your user profile on that system.

The first time that LimeWire will run, it will ask you about which language you want to use, before asking you anything else. (However if you have upgraded from another version, this initial wizard will not appear, and the previously selected language will be kept with your Limewire user settings, stored in HOME/.limewire/limewire.props).

You can change and save to another prefered language as you want, using the last "Change language" option in the "View" menu, where the supported languages are all listed with their native names (allowing easier identification of this list): once you have selected this new language, just exit LimeWire completely and restart it to allow LimeWire use the new language.

Note that some items may still be displayed in English: this happens when LimeWire is not completely translated and lacks a localized resource for it. You can help Limewire by providing the missing translations, see:
http://www.limewire.org/translate.shtml