Ah, thans for explaining the new feature (I think that he 'while processing' part confused me - it just seemed to me that count pages works whether the website gives a word count or not, and I did not look too closely at the title page to see if there was an exact word count or not. Sorry.)
Yes, I can see that using FFF with replace_metadata would be quite messy and not something I could easily work with. There is no need to implement something new for only one person. I'll follow your suggestion and try my hand at a new custom column. Thank you!