The docs read:
When handling the results of a “loadScores” call, event.data in the callback listener is an array of items (tables), each of which contains the following properties:
event.data.playerID – ID of the first player in the request
event.data.rank – Rank of the third player in the request
In addition, the event.localPlayerScore table is accessible for the logged-in player. This contains all of the properties shown above.
So, if the player is logged in, you can get their score value by “event.localPlayerScore.value”. Otherwise you need to use event.data as also described above.