I've run early model Michelin tubeless 28mm tires that aren't hookless approved on 25mm IW hookless rims with no problems. The last one was taken out of service because the bead had stretched so much that it unseated when the air was let out to check the sealant level and would no longer stay seated long enough to reinstall the valve core. I now use Pirelli P-Zero TLR tubeless that are approved for hookless and 28mm tires are rated OK for 25mm IW rims. Regardless of what ETRTO says, follow the manufacturer's recommendations.
I've had the Pirelli tires mounted on a bike for a year and moved the front to the back for another year with no problems.