I saw dreckfresse's OP here https://digiex.net/downloads/downlo...e-disk-2-english-multiplayer-spartan-ops.html and while I wouldn't suggest anyone upload an ISO, I may be able to suggest a solution for his issue that is both legal and supplied directly by Microsoft. 
What many people do not realize is that the Halo 4 MP content on disc 2 is also on Xbox Live. Since Live supplies it as DLC, it is most likely console locked like all other DLC, however it is a completely free download.
I would suggest that the OP do the following:
1) Delete all Halo 4 MP content from the Xbox 360.
2) Create a USA region gamertag on the Xbox 360.
3) Use a XBLA gold trial code.
4) Log on with the USA gamertag.
5) Start the Halo 4 game disc.
6) Choose Infinity MP.
7) You should be prompted to download the Infinity content.
8) Go back to the MP screen.
9) Choose Spartan Ops.
10) You should be prompted to download the Spartan Ops content.
11) Log out of your USA gamertag.
12) Log into your German gamertag and play.
While this is not tested, it should work as the Halo 4 disc is not region locked. I'm making the assumption that the MP content is compatible across versions as it should only be the language that differs and since you'd be downloading the MP files from the USA XBLA server in this case, you should get the English version.
Give it a try and let us know if it works.

What many people do not realize is that the Halo 4 MP content on disc 2 is also on Xbox Live. Since Live supplies it as DLC, it is most likely console locked like all other DLC, however it is a completely free download.
I would suggest that the OP do the following:
1) Delete all Halo 4 MP content from the Xbox 360.
2) Create a USA region gamertag on the Xbox 360.
3) Use a XBLA gold trial code.
4) Log on with the USA gamertag.
5) Start the Halo 4 game disc.
6) Choose Infinity MP.
7) You should be prompted to download the Infinity content.
8) Go back to the MP screen.
9) Choose Spartan Ops.
10) You should be prompted to download the Spartan Ops content.
11) Log out of your USA gamertag.
12) Log into your German gamertag and play.
While this is not tested, it should work as the Halo 4 disc is not region locked. I'm making the assumption that the MP content is compatible across versions as it should only be the language that differs and since you'd be downloading the MP files from the USA XBLA server in this case, you should get the English version.
Give it a try and let us know if it works.

