Downstream channel power level concerns

I am under the impression the difference between the highest and lowest should be 3

There are lots of "rules of thumb" for signal levels, but only Cox can provide the correct range of specs.  I agree with widermouthopen.

Correctables are fine because your modem is correcting codewords.  Uncorrectables, however, are so bad, your modem has to request a retransmission.  You have uncorrectables on all channels.  This is concerning; however, your SNR on the cable looks okay.  Any electronic devices in your house setting near the coax?