I need a modification language

[Bocker]

Hello, old version of SMF that I purchased (hxxp:www.poweriserpages.com [nonactive]) there was one modification which I could not find .Would it be possible to make it in my new forum (hxxp:www.new.poweriserpages.com [nonactive])
Description: Each member in the profile can set the language which preference and show the description and function. But there were other options to choose what language you wants to show contributions. If anyone spoke English and German to follow the posts in both languages.
If someone put in a new topic, you could choose what language you write written directed by the post where it is displayed. The default setting was in a language which had as preferred.
Can anyone make such a modification? Even for multiple languages? How much would it cost?