Yes, they can be improved. The question is how much. The more you go into the shadows or highlightes, the less information does JPG save. This is to save space, because the eye does not see as well in the shadows and highlightes. You cannot get anything in the image that you cannot already see, but you can make what you can barely see more visible. It is up to expermimentation how much you can push an image.
Cropping and rotation will throw pixels away.
In the same ways as you don't have to fix all of your blurs, you don't have to do this. First, it is not finished at all and it will not be inside the Mapillary system. But I will make it so you can easily copy your settings to an entire sequence. Then you can e.g. fix that a dash cam should be rotated and cropped a bit, and perhaps everything should be a bit lighter.