Did the last upgrade of Pages solved your problem? It did for me!
Otherwise, I could access the file in the finder (in 'all documents', you can acess your icloud documents). Unfortunately this doc was not readable anymore: instead of nameofmydoc.pages, I had a nameofmydoc.pages-tf. I could open the package and find all the pictures I had in the doc, but the text was not accessible. I only found a file called 'index.bd', while it is the 'index.xml' that is needed to open a file in Pages. It is possible to use the 'index.bd' to get the text in format .rtf, but that mean you loose the structure of the document... Don't know that's really what you want.
So: if the last update of Pages also solved your problem, that's great. Othewise, it is possible to get the text, but it is not easy and you lose the stucture...