The lack of good table support in Webflow is a major pain, especially for clients/editors that only has access to the Webflow Editor. This is the closest I’ve come to a workflow that can work for not very tech-savvy users.
The designer
Make a CSS style sheet that defines how the table should look like on the published site. Place the CSS styles in the header code. Something like this:
<!-- Table styles -->
<style>
table {width: 100%;}
tr {border-bottom: 1px solid #ddd;}
th, td {padding-top: 10px; padding-bottom: 10px;}
th {font-weight: bold; text-align: left;}
</style>
The Client/Editor
Export your table form a spreadsheet as a CSV file. Use CSV to HTML tool to convert the CSV file to HTML and copy the resulting HTML code. Paste the HTML code into the Rich text field using the Embed tag. Voilà!