lmx to trk conversion is most likely related to export of gps / navigation / track data between Nokia exchange format (.mx) and format specific for CompeGPS solutions (now know as TwoNav).
It might be best to take advantage of some of the dedicated GPS conversion tools, such as GPSBabel or similar. Nowadays you can even find some sites with web app conversion solutions that can translate your tracks between different formats.
Updated: October 10, 2023