Hey Max,
first of all, thank you for the purchase!
If you’re talking about the update I’ve provided in this topic, then yes, it should be possible to link to the blog using this method. The menu item you create should be a direct link to the blog posts page you’ve set in the “Settings -> Reading” admin section; for this, the “link” type of menu item would be most suitable, as it allows adding any URL you want (see the left-hand side of the “Appearance -> Menus” admin section.
Regarding the title underlines: the “line-height” declaration that immediately follows the commented-out line has been inserted to prevent exactly that :) not sure why it does not affect the title styling on your website, though – I can see that it is there in the style.css file. A side-note: I’d recommend using the CSS-style comments for commenting-out CSS lines, as described here – HTML-style comments may sometimes lead to unpredictable results.
Sincerely,
Andrii / Satori Studio