I had a similar question. And I'm still not clear from the response what exactly index_blks_total is and whether it addresses it.
I think I agree that a user is likely to want to see the progress in a way they can understand which means for a single index at a time. I think what you're describing is that index_blks_total and index_blks_scanned are the totals across all the indexes? That isn't clear from the definitions but if that's what you intend then I think that would work. (For what it's worth what I was imagining was having a pair of counters for blocks scanned and max blocks in this index and a second counter for number of indexes processed and max number of indexes. But I don't think that's necessarily any better than what you have)
