I actually found one more problem with the double-click issue: it seems to me that it causes Battle Quest victories to count as victories on Battle Statistics.

I can't be certain that this is the same issue, but I have had the same problems as others in this thread (page not loading when finishing the battle, having to reload etc.) On some occasions when I have unlocked challengers that are available as Battle Quest opponents, the first "regular" victory may be counted as the 3rd or 4th victory instead. When I finally synced my battle pet's stats (https://www.subeta.net/games/battle/stats.php?view=pet&id=1011133&resync=resync), I saw victories against opponents that I have never unlocked, but have fought in Battle Quests (Amalgapede, Angrybeard, Big Banner, Brain Eater, Captain's Ashes, Clive, Cloud Sylph, Coeli, Evil Morty, Grandcrab Jones, JallyFash, Jollyjaw, Meatslab the Resting, Ping, Pylot the Wary, Rottgeist, Scary Singer, Skeletal Warrior, Teef, and Wrole), and only those.