Took me three reads to understand your request. To paraphrase: Add cache type filtering to the Found Date stats.
I think the is a good idea, however I think you need to think bigger - add the option for cache type filtering on all the graphs - cumulative finds by month, finds by month per year, finds by found date, finds by hidden date.
The only snag is that Profile Stats takes an age to load already, and adding more data will make it take even longer.
