1) Would you mind to clarify what SEO analyzer you're using? I don't understand how your SEO analyzer sees the h1 on the landmark-header but miss other two h1 on plain sight.
Do you think caching has something to do with this?
To remove the h1 that is under header-landmark, please log in to your server via FTP and navigate to this directory
\wp-content\themes\x\framework\legacy\cranium\headers\views\renew, there you'll see a file named _landmark-header.php, copy that file to your child theme in same directory, create the folders if that directory does not exist on your child theme.
Then open/edit that copied file, find the line:
x_is_portfolio_item - underneath that you'll see an
<h1> line. That's the one you need to change or remove.
Please keep in mind that I'm only pointing you in the right direction, please understand that it would ultimately be your responsibility to take it from here.
2) I did check your site with Screaming frog SEO spider and it did not find any
Missing Alt Text on your site, not even one image. It finds 1
Alt Text Over 100 character
This means the issue is either a caching or your analyzer which is outside of our control.
While I did take the time to do this SEO check. Please understand that improving your site SEO is outside of the scope of support that we can offer. If SEO is very important to you, I advise that you find/hire someone that is knowledgeable in SEO.
Thank you for understanding,