Currently plugin supports adding HTML as the value in a data table cell i.e. <td> element - the HTML renders (not treated as literal text).
However, it does not do the same with data table headers i.e. <th> element. It treats it as literal text.
This means its not possible to put an image in a column header of a data table, for example by using some HTML/CSS like this article shows.
Not being able to use an image in a column header is limiting in terms of making a table visually appealing for example using a headshot photo of a person instead of simply the text of their name. Allowing HTML in headers will open up a lot of possibilities.
Note, HTML in header is currently supported for simple tables but not for data tables.