When I check my site via SEMrush, it seems to be penalizing me for redundant content, lack of title tags, hq, etc . for each of my blog posts. Although the blog seems like it is only a single page, each post is also a page and there is a redundancy.
I assume there is no "fix" but is this ok, or are there things to do to reduce the penalty?
I wouldn't worry too much on the reporting from a tool like that. The actual effect on your SEO from those elements isn't going to be noticable, really. They're designed to report on any possible issue that any search engine out there might complain about.
What kind of title tags is it looking for? There should be a <title></title> tag on a blog post page.