Quick replace instrument number (or better yet...)

But what does linking mean?

When a track and instrument are linked, switching either one would select any similarly-named track or instrument, and renaming could update both as well.
The actual picking up of the instrument could be fully automatic (akin to auto-capture), or manual via some shortcut.

Isn’t this pretty much sufficient for such a workflow? https://forum.renoise.com/t/tool-3-1-capture-track-from-instrument/34036

If you enable this feature together with the native auto-capture instrument from track, you get a pretty tight integration of tracks/instruments.