We understand the use case and would implement it right away but for technical reasons how our database is designed it's not easily possible at the moment.
When you search your library you basically apply a filter and you are shown all items in your library that match these filters (i.e. implicit "AND"). The results are sorted by the sort option you have chosen on the right (by default it's the date you added the item to your library).
Paperpile does not currently do a search engine like ranking which would make it easy to prioritize items that include the complete search phrases and to enforce it with quotes.