You can use bookmarklets in Firefox to do the very same Google translations that you had with the Google Toolbar. Bookmarklets are bookmarks with JavaScript. Firefox also supports substitution (%S, %s) in it's bookmarks as well as having keyword shortcuts. Other browser have may have keyword shortcuts but they are only available with a search engine. Since you specifically asked about translation the following are directly from the sources indicated later but they are

• Using Google Toolbar features without toolbars - MozillaZine Knowledge Base
  http://kb.mozillazine.org/Using_Google_Toolbar_features_without_toolbars
• Firefox Keyword Shortcuts
  http://dmcritchie.mvps.org/firefox/kws.htm

The Google Toolbar is no longer supported by Google in Firefox 5 and up, you may be able to get what you want from it for a limited time, the directions to install the Google Toolbar were posted before Google actually announced dropping support.

• Enable Google Toolbar in Firefox 5
  http://googlesystem.blogspot.com/2011/06/enable-google-toolbar-in-firefox-5.html
• the-edmeister posted a brief evaluation of the situation
  https://support.mozilla.com/en-US/questions/841736

In any case you can find several alternative solutions, and you can start working on them now, see

• "Using Google Toolbar features without toolbars"
  http://kb.mozillazine.org/Using_Google_Toolbar_features_without_toolbars

I have lost all my bookmark folders when I updated to firefox 5.0. I think they are still there in crash report folder, profile and profile ini. and registry dat. Problem is you can't open any of them it just sets there and tries to load up forever. I hate it, when I see a new update I just keep wondering what am I going to loose this time. It seems every time they update you loose more than you gain. I loved the IOBit toolbar, guess what, it's not compatible with firefox 5.0