Downloaded game title displays as ''My app title in LANGUAGE''

Sorry but most titles will default to the language of the region that they are downloaded in.

No unless you are using a english.disk

If you are talking about the games with gold version you can only download the DE version language independence is only a xbox one feature not a BC

BC titles are region restricted according to international laws

Keeping your console setting at english will continue to restrict your access to bc titles as console language actual location and account location has to be the same for ALL bc titles

Only way around it is disk based games or games with multi language support in the menu which few games do

What game is it? And this is on Xbox One? I would recommend navigating to the store page for the title, if it's not updated in your "My Games & Apps" section, but still associated to the account, it should let you download it directly.

You might want to check if the title is also already in the Installed section of My Games & Apps? When you redeem a game, depending on your settings, it could automatically start to download the title, so see if it's listed there or in the Queue already
downloading.

Changing the language of the console doesnt affect games on demand

very few triple a titles support multiple languages

since you arent in a english supported region you cant change the download to anything else

bo2 only supports one language per download

My console is 4gb without kinect the power supply light is green, and as for what is displayed well for downloads it's the my games section and for games on disc it generally the loading screen before the title screen.