Errors and warnings

I have created a new site using the Supermag theme, which I am very pleased with. However, when I check the site with validator.w3.org I get one error and four warnings which I believe may be related to the theme as follows:

Warning: the “banner” role is unnecessary for element “header”
<header id=”masthead” class=”site-header” role=”banner”>

Warning: element “nav” does not need a “role” attribute
<nav id=”site-navigation” class=”main-navigation clearfix” role=”navigation”>

Warning: element “main” does not need a “role” attribute
<main id=”main” class=”site-main” role=”main”>

Warning: the “contentinfo” role is unnecessary for element “footer”
<footer id=”colophon” class=”site-footer” role=”contentinfo”>

Error: bad value “designer” for attribute “rel” on element “a”. The string “designer” is not a registered keyword
rel=”designer”>

I am concerned that these may affect my SEO. Is there a way of fixing them?