Hugo,
Maybe start here to clear up which ‘Partitions’ we’re talking about…
I only have a vague memory of Partitions. Things have come a long way from then. It looks as though the plug-in gave way to the stack; and that the stack then attracted these possible replacements.
Maybe contacting Kuler themselves might produce something useful.
If the site is published (on a server somewhere; or exported when you were uploading the last time), you’ll surely be able to select and copy/paste the actual content into a text editor, format and update it then re-incorporate it into your new site.
Will your RW 5 project open? If so, you might well be able to do the same thing (select, copy and save) the text which is otherwise trapped in its pages.
In the worst case, you’ll probably be able to open the project in the Finder and ferret out the relevant files/text at the filesystem level.
Good luck; let us know how you get on!