One of our engineers wanted to know if it was possible to get notifications if code was changed for any folder with that matched the term "X". I mentioned that he could just find any folders with the term but there might be times where a new folder is made without his knowledge.
Currently it isn't possible to get notifications for search results in FishEye. There's a feature request related to this here: https://jira.atlassian.com/browse/FE-4958 - please vote for it and describe what functionality you'd like to see.
Depending on the exact functionality required you could consider a solution that polls a REST resource periodically to search for interesting new commits (like https://fisheye1.atlassian.com/rest-service-fe/search-v1/queryAsRows/firebird.json?query=select%20revisions%20from%20dir%20%22/%22%20where%20path%20like%20%22**/test/**%22%20order%20by%20date%20desc%20group%20by%20changeset%20return%20path,%20revision,%20author,%20date,%20csid to search for new files in a 'test' directory in the selected repository), and fire notifications based on that.