I just want to add my 2 cents on this. Using color for semantics is one of my pet peeves, when the colors are not accessible to me. I have a red-green color deficiency and you are most definitely not the only one @askans . Wikipedia says red-green color blindness "…affects up to 1 in 12 males (8%) and 1 in 200 females (0.5%).
Where I noticed this in n8n was on the individual workflow execution lists, where red and green are used to distinguish successes and failures.
The global execution list, /projects/{projectId}/executions, has the best semantics, for me, as the rows of a failed run are highlighted with a color. Successes, which is the expected outcome, are not highlighted with any color, as they indeed are unexceptional.
On the individual workflow execution list, workflow/{workflowId}/executions/28, all rows have a color attached on the left edge. The nuances of red and green used here are impossible for me to tell apart, making it hard to find an error with a quick glance. Even though a failed run also have a small status text saying “Error” in red.
I used Claude Code to take a stab at how it could be improved (PR against my own n8n fork here). As a new user I am limited to adding 5 screenshots. The most notable changes and improvements for me are:
Workflow executions list
In the current design the list is not skimmable for me. There is no difference in color between success and failure.
Existing
Updated
Workflow execution statuses
The exceptional cases stand out from the expected successful run in my suggestion.
Existing
Updated
Claude Code wrote a whole treaty on color theory, contrasts between colors and why blue is a good replacement 
I don’t have the knowledge to know how much truth there is to that, but it aligns with what Github do for instance. And the colors definitely work for me.
The work above only addresses my concern, and not the points you mention @askans. But nevertheless, I think both of our asks is to make the design more accessible for people with various vision deficiencies 
