Hi,
The fix explained by iedwards (
www.hikashop.com/forum/checkout/877720-e...too-soon.html#207581
) should still work, however, you have to add it to the sub_block_login_registration.php view file for the new checkout while resgistration_bootstrap.php he mentions on his message is only for the registration page, which you probably aren't using and only with the "use bootstrap v2 mode" activated, which is disabled by default.
Regarding our inputs and forms respecting the specs, as far as I can read on your link, our form and inputs do respect the spec.
It is totally valid to add autocomplete="off" to the email confirmation input field, and not to add anything to the email input field.
From what I can read, the problem is with the browser filling the email confirmation input field when it should not and with a wrong value on top of that.
Using onsubmit rather than onchange would make it less of a problem, but still a problem since now the customer would have the error when clicking on the submit button.
Also, when the browser works properly, it's normal that it warns you of the problem when you finish typing in the email confirmation field, and not when you click on the submit button. So doing that change makes the form less intuitive for everyone else.
Note that you can easily do that change on your own website in the file sub_block_login_registration.php via the menu Display>Views.