@Klaas this plugin does not actually care what font you are using. The only reason I say it works best with a monospaced font is because spaces are used to pad cell width. This is best explained with an example.
| One | Two | Three | Four |
| _— |----------------| ------ | ---- |
| 1 | Longer Content | 3 | 4 |
| some | 2 | | |
| One | Two | Three | Four |
| ---- |:--------------:| ------ | ---- |
| 1 | Longer Content | 3 | 4 |
| some | 2 | | |
That’s the exact same text. But notice how in the monospaced font (the second one) everything looks all nice and lined up?
So like I said, you can use any font you like, it just looks a little better in the non-rendered mode in a monospaced font.