The explanation is fine.
It just seems to overcomplicate things to make two distinct starting lines for each and every distance for a rail or no rail.
That track must be all marked up.
I assume the track was originally marked to be run without a rail and they revised each starting line when a rail was added. Easier than resurfacing the track.
I guess it's similar to running metered events on a yards track.
But I am used to seeing either a 400m track or a 440 yard track, not a 400.6 m track.
I have been to a lot of tracks and never seen this arrangement before.
I'm ok with the times being legit if it was originally configured to not have a rail.
In most cases, they'd throw a rail down and keep the lines the same.
Always better to run farther than risk running short.