After downloading all languages (with language as folders), use this
poorly-optimized script to merge those files back in place:

    # Make a temporary directory
    TMPDIR=$(mktemp -d -p ./)
    pushd $TMPDIR

    # Extract files
    unzip /path/to/autofill.json.zip

    # Remove region from language directories
    for dir in $(find . -depth 1 -type d -name '*-*'); do
        mv $dir $(echo $dir | cut -c1-4)
    done

    # Move JSON files back into their language directories
    find . \
        -type d
        -depth 1
        -exec mv {}/autofill.json ../src/locales/{}/autofill.json \;

    # Clean up
    popd
    rm -rf $TMPDIR