When inserting any text symbols representing rhythm notation, keep in mind that it won't always be displayed properly on other devices or platforms. As long as it's just intended to your own device, there's no problem. As a workaround, when I need to share a chart that includes important rhythmic notation, I always share both the iReal pro html file and the exported PDF. The PDF is a snapshot of what your chart looks like on your device, so any text notation will always be displayed properly on any other devices or platforms.