the widget widths are set with CSS, but usually the div#sidebar width is set and that controls the widget width, for example here on buddypress.org:
`
div#sidebar {
width: 224px;
}
`
It is possible to use qtranslate to get a multilanguage buddypress website, however, there are issues. When using the non-default language, the ajax-loaded content will display a “No content found” (ie: “There were no groups found”) warning in the default language. Also some items in the ‘activity’ listing do not get translated properly ‘sometimes’, for example, I am using Spanish and English and in the default list produced on the activity page it shows the same message sometimes in English and sometimes in Spanish, it seems pretty random, I haven’t done any investigating why, yet. So while it looks like a possible solution (qtranslate & buddypress), it definitely needs some work.