You can insert waypoints 'on the fly' in the GUI using the button 'w', but modifing them means, you have to edit the MySQL database directly. For most of the 'normal' users, this is already too much to ask. Moreover, it would be easier to fix a waypoint's position via GUI, than manupulating coordinates in a database.
It would be also very usefull, if one could setup a default type of waypoint to insert by pressing one character.
An other usefull feature would be, letting the software pop-up a message, or say a message (if festival is available), by reaching a per-waypoint-type settable distance.
Have a nice day.