Here are some websites that may help you in your research:

Christmas Around the World
The North Pole: Christmas Around the World
World of Christmas

Country
Greeting
China
Sheng Dan Kuai Le
Denmark
Glaedelig Jul
Finland
Hauskaa Joulua
France
Joyeux Noel
Germany and Austria
Frohliche Weihnachten
Greece
Kala Christougenna
Hungary
Kellemes Karacsonyi Unnepeket
Italy
Buon Natale
Japan
Meri Kurisumasu
The Netherlands
Zalig Kerstfeest
Norway
Gledelig Jul
Poland
Wesolych Swiat
Portugal and Brazil
Boas Festas
Russia
'S Rozhdestvom Khristovym
Spain, Mexico, and other Spanish-speaking countries
Feliz Navidad
Sweden
God Jul
United States, Canada, and other English-speaking countries
Merry Christmas