The short version:
Since 3.8.x, there's a new feature in track editing: "Convert to navigation waypoint". This is very nice, however I don't see why this is restricted to the specific set of navigation waypoints - it would give the user more freedom to be able to create any type of waypoint in an existing track, the same way this is possible while recording a track.
The long version:
I'd like to explain this a little more, but for that first some term definitions (I know some people will disagree, but I'm trying to stay close to the way Locus uses the words):
POI (points of interest): The points defined globally in Data > Points
Trackpoints: The individual points that a track consists of (with or without timestamp - not important here)
Waypoints: Specific points that have the same attributes as POIs, but belong to a track and will be shown/hidden together with the track (cannot be done individually).
Navigation waypoint: Special waypoints that trigger specific actions (speech output, etc.) in Locus while navigating. Otherwise, they behave like waypoints (as far as I can see).
Now while recording a track, I often use the ability to add waypoints to mark specific actions (like "put on climbing gear", or "short rest") that make no sense as a (global) POI, just in context of this track. However, when I forget this, I have no chance to do this later (after the track is finished), even if I still remember the exact location (some people pointed a workaround out to me, but that includes setting a POI, hiding everything else, exporting, importing, deleting POI - much too complicated...).
Also for planning routes, it would be very helpful to be able to add arbitrary information to a point, like "climbing passage", or "rest here", that doesn't trigger a specific action, but helps planning.
I'm pretty confident that technically, it shouldn't be a big deal, as there's already a conversion to a waypoint now, and the dialog for adding also exists (just only while recording).
So I hope many would find this helpful and will vote for it, to make planning and editing tracks with Locus even better :)