Fiddler Everywhere needs to allow us to search across all requests.
Can you clarify what you mean precisely by searching across all requests? Does that mean a search functionality that traverses? However, the currently captured traffic (and filtering only by given criteria) - if that is the case, such feature is already present via the filter options. For example you could filter by your search criteria using some of the Live Traffic columns (like Host or status) and you will end up seeing only the session you need. Filtering will also show new upcoming sessions that are being actively captured.