Suggested feature: To be able to set a playback speed for rewinds that is different from the regular playback speed.
For example, you might set the regular playback speed at 1x, and the rewind interval at 15s, and the rewind speed at 1.5x, so if you missed a word or 2 you can go through the 15s faster.
Add an option in the app settings, next to where you set the rewind interval. This could be a switch that adds a second slider in the main interface. Alternatively, it could be a multiplier of the main speed.