Thanks to all. Your answers helped.
FYI I am changing my whole process. I am going to delete my iCloud backup and cancel future backups; they consume too much space anyway in Apple's attempt to make us purchase more memory. Also, as several have noted, the iCloud restore process is antiquated. I am beginning to be sorry that I ever went to an Apple platform, but that's another story. I have learned my lesson, so here is my future process.
- Use iMazing to backup my iPad Pro 12.9 3rd gen to my PC. This helpful software is user friendly.
- Save my files in original format on my PC using iMazing for easy transfer back to my iPad. Because I have been doing this periodically, I was able to retrieve most of my lost pdf files. 😁
- Also, save my files on DropBox in original format for easy retrieval. I have sufficient free space.
Thanks again for your help.