A true temperament isn’t just about compensating for the string mass differences but also for their differing intonation points. A true temperament won’t get to the same level as a movable fret system but it does also compensate to a certain degree for the differing intonation points across strings at different tunings (what it refers to as speaking length which captures both point to point length and mass related deformation length). They’re different but inherently associated issues.

More information is here https://www.thatguitarlover.com/blog/what-is-true-temperamen...

But this is also why I mention both fret compensation systems in my original post.