[drowned12]

Loosen the bumpers near the latch. If the hood doesn't latch anymore or the hood is not flush to the fenders then you've gone too far.

EDIT: By bumpers I mean the rubber knobs that the hood touches. On the 8G there are 4 of them. 2 are adjustable like screws, 2 are not. For the 2 that are not I used some foam tape to get the fit tighter to ensure the hood doesn't vibrate at 100+.

http://www.driveaccord.net/forums/attachment.php?attachmentid=447978

 

[drowned12]

The flexing I saw was at the rear of the hood , just in front of the base of windshield, no bumpers there. Many car companies are designing hoods to give in pedestrian impacts, Honda may have went too far in this case.

If the hood isn't being supported on all of the 4 points then it's going to be more likely to flex and it might just be most visible near the windshield. If -and it's a big if- there's a design flaw it's not going to be resolved anytime soon so the fixes are first try the bumpers, then add some foam tape along the seam where the hood and the cowl contact: https://www.homedepot.com/p/Armacell-2-in-x-30-ft-R-1-Foam-Insulation-Tape-TAP18230/100539553

 

[drowned12]

I’ve had my 2018 Sport to the dealer twice for the same flutter without a fix. I have the black accord and it seems much more noticeable while driving with the glare.
There aren’t any adjustable bumpers or dampers on the 2018. The dealer took out 3-4 other 2018 on the lot, ALL with the same flutter over bumps and at the higher speeds. Conclusion is design flaw and have to wait for a service bulletin for a fix.

Wow, all of the bumpers are fixed? Break out the foam tape to act as a shim, wouldn't be surprised if something like that ends up becoming the official "fix" until it's fixed in the production line. They're not going to be replacing hoods for something that is likely just a cosmetic issue.