You be the judge of whether you think this is worth the time and effort and see if you think that my reasoning here makes sense to you. I am trying to determine if a "clean slate" of Pages files in the cloud will allow Pages to function properly on the iPad. In essence, this is like starting all over again with iCloud.
Download all of the documents from Pages in iCloud.com and store them (to hopefully be used later) in a folder on your desktop.
After all documents have been downloaded for safe keeping to your Mac, delete the documents from iCloud.com and close the web browser.
Launch Pages on your iPad and see if ...
1. The setting for using iCloud will stay enabled.
2. Pages will open and let you create a new document
3. The documents will upload to iCloud.com
The way to check on number 3 is to log into iCloud.com on your computer again and see if the files are there.
If all three things check out, add the documents in the folder to iCloud.com one at a time and see if Pages still works on the iPad and if it still syncs with iCloud. I would drag the documents into the browser window - one at a time until you run into the crashing problem or any other problem. If you have a problem, I would assume that I was the last document added to iCloud.com that is causing the problem. I would then remove that document and check it for any errors that I could find and maybe edit it somehow, or re save it and see if it will work after that.