I can’t access your shared site as it just displays me the message “Desarrollo
Please make sure that your website is accessible or would you mind if I log in to your site and access it? If this is ok then could you please temporarily share me your site admin login details privately by adding them in the box having text “Enter your private content here (only you and forum moderators will be able see it)”?
I understood what you want to achieve and to achieve this, you have to develop custom code in the below Jevelin child theme file.
Developing custom code for custom functionality is beyond the scope of support that we provide here. Please see https://themeforest.net/item/jevelin-multipurpose-premium-responsive-wordpress-theme/14728833/support
If you are not a developer then you can consider hiring a developer to develop it for you. You can hire a developer from any freelance site. Shufflehound recommends the developer https://www.upwork.com/freelancers/~011652ffec8865c6d5
No, it is not an SEO issue as the Blog text is displayed in h2 tag and the article title is displayed in h1 tag.
Also, you can change that Blog text in the theme settings as shown in the attached screenshots.