For the general game flavor and the new mega events, the xml files that contain the English text are currently located in the main xml folder (Steam\steamapps\common\Galactic Civilizations III\data\Game) instead of the English translation folder (Steam\steamapps\common\Galactic Civilizations III\data\English\Text).
This is not a real bug, but could be a hassle if you are running with a translated version, or if you are doing a translation yourself.
General flavor file:
Mega Event flavor files:
The accompanying MegaEventText xml file are in the correct folder, but there seems to be two for the pirate colony event (PirateColonies_MegaEventText.xml and PirateColony_MegaEventText.xml). The PirateColony_MegaEventText.xml seem to be the correct one.
And there is a DistantRecourses_MegaEventText.xml which seem to be a wrongly spelled superfluous version of the DistantResources_MegaEventText.xml file, since there is no Distance Recourse Event.