This ticket builds off of LIVECOPY-254. To simplify things we have a master with 2 languages and a slave which should only serve a single language. In the slave the single language to be served is not the default one but instead using _fr on the properties which hold the content.

When the language parameter is passed it appears to be ignored and just shows the default master language.

Reproduce
Site "be", which is the master and has "nl" and "fr" languages set up ("nl" is default)

Site "be-fr" is the livecopied site where I only want to server french. However, "nl" still occupies the default properties because it was copied.

"be" site:
When I query the rest API with http://localhost:8080/.rest/delivery/website/be?lang=fr - the "nl" content is shown. When I put the lang=all I get both languages back as expected (I've attached a file with the request response for lang=fr and lang=all for you to see).

"be-fr" site: When I query the rest API with http://localhost:8080/.rest/delivery/website/be-fr?lang=fr - the "nl" content is shown. When I put the lang=all I get both languages back as expected.

The pages are working as expected within the Magnolia UI, all languages are displayed correctly on page render and in dialogs.