Because the tests are not standard achievement tests, there is not much to go on to provide additional interpretation. That said, the words per minute is a fluency measure...

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National Percentile Rank 74th percentile... Words Per Minute 155
Looking at two reading fluency tables easily found online with a websearch (A to Z and read naturally), these tables seem to agree that 155 words is roughly a 5th grade level.

The read naturally chart indicates that a winter score of 156 words correct per minute is at the 75th percentile among 5th graders, and a spring score of 168 WCPM would be 75th percentile among 5th graders, with growth of approximately .9 WCPM each week.

Looking into such measures may help you informally assess your child's progress in the interim.