I could not replicate the issue on my end, please clear your caching features because we are still seeing old version of X on your site. I advise that you CLEAR and DEACTIVATE all your caching plugins/features while the site is still in development stage.
<br> tag works inside the RAW Content element, maybe this did not work on your because you nested shortcodes and other unnecessary HTML tags inside the RAW Content. You could have made your layout much simpler if you did utilize the Text element and Headline element.
These elements provide you with all the text formatting and text styling option.
This should have saved you from wrapping your content inside a content band shortcode and/or
<span> and other tags.
Cornerstone / Content Builder - Elements
See Elements in action
Hope this helps,