[yarper]

Unfortunately it's not just the manuals that are in English.

The prior work is written up and signed off in English, the pilot/cabin tech logs will all be written up in English. The current AD/SBs (usually extra maintenance/fixes) will all be issued in English and so on.

Further to that you have to write the work up in English, and get it signed off and declared safe to fly in English too.

Other parts of the world already operate on non-English, e.g. Russia. They use the same aircraft we do but in an entirely different framework. However their framework does not necessarily apply if you want to get an aircraft cleared to fly in Europe (EASA) or the states (FAA).