One answer might be that there is no transitional or inventory identifier for UFO's in that place. The objects may have existed there, but they were not named. For example, the bearers of the American inventory are renowned for the aggressiveness with which they apply their inventory. The transitional identifier of UFO combines the broadly comprehensible aspect of a flying object with the innocuous transition of the unidentified. A mere 701 remained marked by transitional identifiers.
Objects make up the substance of the world.
That is why they cannot be composite. A transitional identifier which lacks a robust, anchoring metaphor remains inescapably composite and is not compelling. It can thus be glossed over in most cases. Another answer may be that there have been such sightings in India, and the transitional identifier of UFO was applied to them. But the conversation was quashed by bearers of the inventory, lest that conversation overwhelm the communicative web which supports the inventory.