I found the following thread regarding color blind accessibility, and found it has not had an update in 5 years, and the current version of Testrail does not appear to have a way for a user to adjust their color scheme.
I will agree that using color to differentiate is not wise, though adding the word failed/passed/skipped/etc adjacent to the step in question could be a possible solution to address the accessibility concerns. I do see a tooltip is present to indicate which step failed, though this could become increasingly tedious the more steps that are present, and tooltips can only be viewed one at a time.
Could we get an update? Is this something we can expect soon?