I think The Little White Bird must be in the public domain, although maybe not quite yet in the UK. Certainly, you can read it online, free of charge, by accessing this website:
http://www.literature.org/authors/barrie-james-matthew/the-little-white-bird/
or this one:
http://barrie.thefreelibrary.com/The-Little-White-Bird
or this one:
http://www.fortunecity.com/tinpan/quickstep/1103/little_white_bird.htm
Take your pick! I don't know if there are any online translations available, but I imagine anyone can set about translating the novel if they wish. It might be as well to check with the original publisher, however, (in the UK, Hodder and Stoughton) because copyright law might vary from country to country. For example, in the UK I think works of literature become free of copyright 70 years after the death of the author, whereas in the US I think it is after 50 years, but please don't assume this. I am no expert.
Good luck, anyway.