No, as far as I can tell. There's no option in the current text editor. Only alternative is to create an image to mimick <hr>. If you don't want to use Photoshop or don't have it, you can easily do it with https://placeholder.com/5. Just specify size and color, and it will generate an image.
- Here's a 600x1px gray line: https://placehold.it/700x3/cccccc/ccccccc8
- Here's a 700x3px red line: https://placehold.it/700x3/e10c1e/e10c1e5
Note you want to include the color twice, once for background and then for text color. It adds text into the image, so coloring both the same color makes text invisible.
I do hope Tribe will extend text editor functionality.