Fortunately, the Jora you need can come from anywhere. Unfortunately, your only going to be able to buy one from a Guild Kiosk or find a Potency Node and harvest one. I see them from time to time for reasonable prices, but sometimes they are expensive. Also, 99% of the Glyphs you make will use one Potency at each level, and I think Jora is the one. So, if you see a stack of 10 or 20, buy them if possible if you plan on doing a few L1 Writs.

What you can try is this, log off and exit the game, then reload it. See if the nodes come back. If they don't, then just abandon the certification quest. When you go back to the quest giver you will get the quest again. Cool thing, you get to keep the runes you already have.

If you don't want to abandon the quest and get it again for some reason, then message me in the game (I am on the NA server) and I can help you out with a Jora. But you won't get it until this evening.