It varies - but this is really the first time we've had a lot of major world and species material thrown to use before release, so it is possible they intend to write more... however, the races they published in the first round looked 'complete' for what they were, and as though they were intended to be a replacement for what we have, which would be disheartening if true. The Fairy block I quoted above is the fully released official information for that race, in its entirety, so I'm not willing to rely on assuming that they'll fill in more flavour between testing and release, without making a point of it.