Searching some pre Eve Gate archives seems to suggest that -Kostorg- may be an word from the Earth group of people called Russians or Bulgarians.
Searching the Bulgarian spelling seems to return a large quantity of possibly scholarly articles or literature. This may be of more utility than my other finding discussed below.
Searching the Russian spelling seems to return early Earth material called “pr0n” of the multiple male group coitus variety. Search carefully! It does appear this may be because the the translation software adds a “y” to the end - Kostorgy- which the search string tries to render as - Kost Orgy - Kost being “male” or “men”.
**One must wonder about the timing then: Russian Invasion
Neither Bulgarian or Russian are areas of my research, perhaps someone here is better equipped to look into this.