Yahoo language

have you tried something like
http://au.yahoo.com/

or

To switch languages, just click on your preferred language on the sign-in page – the link is in the middle toward the bottom of the page.

or

To change the preferred language for your profile, visit http://profiles.yahoo.com/tos_reset.php and follow the instructions there. Be sure to review and accept the Terms of Service presented.

To change the preferred language and content for your Yahoo! account generally, visit https://login.yahoo.com/config/set_intl. There you can select among the language and content choices. Follow the instructions and be sure to review and accept the Terms of Service presented.

hope this helps

you can change from account settings