var lead = document.querySelector("my-app").shadowRoot.querySelector("hive-gamemode-leaderboards");
var vaagrid = lead.shadowRoot.querySelector("vaadin-grid");
var prop = gameModeConfigs[lead.gamemode].leaderboard[0].key;

Object.entries(vaagrid._cache)
.reduce((res, [key, curr]) => res.concat(curr), [])
.filter(a => a.prev && a.prev[prop])
.sort((a,b) => b.prev[prop] - a.prev[prop] || 0)
.filter((a, i) => i < 20)
.map(a => `${a.name} : ${a.prev[prop]}`)
.forEach(a => console.log(a))