I've installed the German language package - but did NOT re-compile(?) (what the installer has asked for).
But when I've started DOpus 8 - it has done something and after that I'd a mixed mode between English menu's and German things.
Please look on the screen shot.
I've also tried to select the English Package and re-started - but it didn't help.
However - I don't know what has happend during the weekend - but currently I have my full English version. But something doesn't work correctly during the language change ...
After selecting a new language, accept the 'change language' choice. After a restart, Opus dynamically converts all the standard toolbars, buttons and so on to the new language. If you have edited toolbars etc to add your own custom items, these may not be converted since Opus can only convert the original texts (it's not a translator program:).
As Nudel says, if you have toolbars which have not been converted, go to where these are stored in the program home folder or your log-on name's personal applications folder and delete the toolbar files. On a restart Opus will recreate the toolbars required.