How can the playable progress be higher the completed one? Unless 'playable' progress is speaking to the percentage of the completed progress percentage. ... I.e.: 90% playable but 80% completed means 90% of the 80% is playable.
The idea there is that a system can feel more complete to the player than it is in terms of overall development. Feature A might need to be redone so that it works with new feature B. Take the two starting maps for example: these terrain generators were hand-tuned to give a certain map output so that we could play the game without having to have the overworld system finished. This work, however, will have to be redone in a different way for the final product because ultimately we will want the maps to be much more random, generated based on starting position selected from the world map. Therefore the game feels more playable than it is, in terms of those systems.