If MS really manages to bring around 20 games per month we'll be at 400 by end of next year. Likely with most of the exclusives.

the console recognizes the 360 disc if it's in the Xbox Store's database and then downloads the game from there, since the games are slightly modified (I remember reading an interview about them having to rewrite the executable files).

While I'm not 100% sure I think there's only one version of each game available to download, no matter what region the 360 discs are locked to. Thus including all the languages that used to be split up. (Except for versions that had to be altered to see a release in Germany, Australia, Japan etc.)
Would be nice if someone could confirm that eventually.

EU version is EU. So you get german for Mirrors Edge for example if your One is set to german and english if its set to UK.
I still have to try Fable 2 because the german version just had a german dub.

You cannot recompile already compiled code. Any X86 compiler has no idea what to do with PPC code.

The word you are looking for is "PPC disassembler". This is the first step in the process. There are probably another 10 steps I can think of before you can "recompile" (which would then be called an "X86 assembler" I suppose.

"Compiler" (or "recompiler") is the correct and accepted term. Similar to what the Java virtual machine does to byte code, or what the the Dolphin emulator does to PPC code when you run an emulated game on your computer for the first time.

I can't play Rare Collection 360 games on my XOne because it won't download my profile when on 360 mode. Can someone help me with this problem?