You are correct, At present, LightBurn will produce boundary tracing and does not currently support center-line trace results.
I also point your attention to the upper-right header of the forum where you will find a link to our feature addition voting system. You can add your support for center-line tracing support there.
Center-Line Trace is already gaining votes so add yours via this link: https://lightburn.fider.io/posts/371/trace-center-line-option