How to index Evernote notes with LaunchBar?
I found this question and it made me go look for an answer! What I found is useful, though not directly addressing your question, it does provide the functionality. Perhaps someone coming here will find it useful as well.

To Search Evernote from LaunchBar

With LaunchBar 6.4 and Evernote 6.0. 


Fire up LaunchBar 
Call up Evernote by typing a few letters to select the app. 
Press Spacebar. A text box appears 
Type in some search text and press Return.


LaunchBar opens Evernote with a search in progress.

That is very slick for me.