Hey David,
to get the diagonals to match, you only need to loosen two adjacent feet of the machine (let’s say, the two front feet), and to shift them between right and left (with X axis slid to front, and its bolts loosened additionally)
Further reading
The so-to-speak “official” thread in this forum about rectangularity of the machine is “Is your router frame a parallelogram? Mine was! ”