I came up to the same thought when I added this possibility to display a right label, mainly to provide a similar user xp with the Android progress bar. If we set the right label before, a user won't have the opportunity to override the right label. Another solution would be to define 2 functions: 
- `formatMessage(percent)` : current report function without the code to format the right label 
- `formatRightLabel()` : specific code to format the right label.