In terms of accessibility, you could go one better than Flow using something like https://michelf.ca/projects/mac/sim-daltonism to get an idea of how contrast between success/failure icons looks for people with various forms of colour-blindness. Flow's success/failure icons look very similar at a glance with the Red-Green Sim Daltonism app filters applied.
One suggestion from the above is using both colour and texture to provide contrast. Or perhaps an option for users to swap out icons to another colour combo (with a few options) to provide the necessary contrast.
As with the https://[region].flow.microsoft.com/manage/environments/[id]/flows/[id]/details page, a green tick icon next to successful Flow runs or a red alert icon next to Failed Flow runs would make it quicker to scan recent activity for a particular Flow.
In terms of accessibility, you could go one better than Flow using something like https://michelf.ca/projects/mac/sim-daltonism to get an idea of how contrast between success/failure icons looks for people with various forms of colour-blindness. Flow's success/failure icons look very similar at a glance with the Red-Green Sim Daltonism app filters applied.
This article gives a good overview on designing for colour blindness: http://blog.usabilla.com/how-to-design-for-color-blindness
One suggestion from the above is using both colour and texture to provide contrast. Or perhaps an option for users to swap out icons to another colour combo (with a few options) to provide the necessary contrast.