I’ve been checking the Wiki every so often, and it now states that you can find the Juvenile electric wyvern in Verdant Brink, Canopy over the Pact Encampment – on a large rock south. I am anxiously awaiting nightfall to see if this is actually true, I will report back. Here’s the link to the Wiki page.
https://wiki.guildwars2.com/wiki/Juvenile_Electric_Wyvern