while working on bug 1219505 I noticed this, it just looks wrong. when a search is initiated from a search suggestion entry, it should increment the "search" / "urlbar" UITelemetry probe. Currently only keywords and typing+enter are incrementing that countable, while from the searchbar any search action does. Thecnically should just be matter of invoking BrowserUITelemetry.countSearchEvent with the proper arguments. That will give us more reliable data for the search volume from the location bar.
fixed by bug 1226629