hi,
filtering is an advanced feature and takes from trial and error to get it working.
as for directory filters, that is already documented at https://rclone.org/filtering/#how-filter-rules-are-applied-to-directories
as of now, rclone, via a bug i discovered, does support simple regex patterns.
https://forum.rclone.org/t/full-support-for-regex-for-filters/26883