I believe, many developers using WP_CONTENT_URL (and WP_CONTENT_DIR) to relocate the content path.
HOWEVER this is causing problems with plug-ins hard coding '/wp-content/' (!!!)
So far I found in class-url-changer.php
To avoid an extraction every time I need my path name, I have defined WPCONTENT (i.e. 'cms') ...
Since I'm having problems (stella is changing my template path by inserting the a /en/ when switching to English) ... I'm hunting the bug and hopefully will find it soon because I love your approach of multilingual WP.