I’m not English and Screen Readers are not in use here.
My question is:
Is there any benefit to use Role Attributes if Screen Readers are not important for us. Is it good from SEO purpose or it’s just for accessibility?
Unless your application is controlled and internal (i.e. you know noone will use one) then you need to support the accessibility part of your website. Just because noone uses screen readers 'there" doesn’t mean noone does elsewhere.
At this point, author-set roles are just for accessibility.
Many elements may already have a default role-- for example, <input type="checkbox"> have a role of “checkbox” anyway, though whether this is measureable depends on the browser. Most newer browsers support HTML roles, but older ones like IE7 won’t.
So far as I know, SEs haven’t gotten on board with doing anything with roles… but I don’t see why they couldn’t, so I figure so long as they care about content, they may in the future start adding them to their understanding of HTML semantics.