This is my interpretation of the ref board in simplified version
I drew the outline into eagle for fun (I do not even have a 3458a)
left version is the original (I shamelessly copied this from pictures off some posts and from google), including the LTZ strangely off center
the right side is if the 2 are aligned and shifted to the edge.
in both, all main parts and holes sit on 25mil grid exactly
I think the plastic cap being off center looks to me like they "ran out of design time" or something to that tune. because if you slightly shift the LTZ or the cap, it fixes the problem (and save some electrons haha !)
look at your own drawing, you can already see the cap is not center with LTZ
everybody copies this exactly. I was hoping someone will already do one that is centered
since your version is mm, everything is not in alignment esp if the error is in 0.1mm. since everything is THT component, everything needs to sit around multiples of 2.54mm or 1.27mm. but since everything in 3458a could be 0.1mm tolerant, maybe it doesnt really matter.
edit an updated stolen overlay in PNG with more details (1pixel=1mil). another weird thing (which I guess is common?). the oversizing of TO126 pads so that the pin space is 2.54mm/100mil and not according to the part which is 2.28mm/90mil.
the accuracy of the overlay is only as good as the degraded processed photo. but in this version, there is more to see as pins/parts are highlighted vs 25mil grid scale