Colour is not supported and transparency is not supported in the traditional sense. To create your own textured brush, you must prepare your texture file ahead of time, either in Harmony or in a third-party software, such as Adobe Photoshop. You will understand why when you work with bitmap brushes on bitmap layers, where it is possible to have both a textured brush tip and a paper texture. In other words, we are attributing the texture not to the tool, but to the texture of the surface that is revealed when a stroke passes over it. In Harmony, when using a textured brush on a vector layer, the texture of a brush is referred to as the Paper Texture. In the Brush Tool Properties view, you will find a series of default textured 'brushes', but you can also create and import your own custom collection. In Harmony, you can use the Brush tool to draw bitmap textured lines.

Drawing with Textured Brushes on Vector Drawing Layer