Re: Language
If some strings are not translated it’s cause they are missing to be included nto the internationalization functions, and this is a bug, You can open a ticket on trac about untraslated strings so they will be corrects annd included into pot. file.
For info about internationalizion and stuff you can refer to WordPress COdex searching for internationalizazion and localization, the info you will find there arcan be applied to bbpress also.