for FILE in languages/messages/*.php; do sudo sed -ri "s/(['\"])watchlist\\1(\\s...

for FILE in languages/messages/*.php; do sudo sed -ri "s/(['\"])watchlist\\1(\\s+)=>(\\s+)(['\"])(.*?)\\4/\\1watchlist\\1\\2=>\\3\\4\\5\\4,\\n\\1my-watchlist\\1\\2=>\\3\\4\\5\\4/" $FILE; done

php -l says they're all fine, looking them over they seem to all be fine.  Languages that already had this update individually have doubled entries, but that shouldn't make a difference and a run through rebuildMessages.php should fix if it annoys you.