I wouldn't say that the taillights are of minimum quality, they were just priced really well ($165) but I think Genuine Toyota Taillights for Corollas would probably be 2x more expensive. And the only most convincing place I could find these taillights were Ebay, only one vendor had them, and charged an additional $60 for shipping. I didn't doubt ZestJDM because ZestJDM sponsors this website and 9thGenCorolla (before it shut down). That said, when I asked people where they got their taillights, they referred me to ZestJDM.
Now to follow up on my problem, even though ZestJDM doesn't handle certain areas of Customer Service they still sold me a part I'm happy with, and the problem isn't even a major one. After asking different people who have had the same problem, even on OEM taillights, I've agreed that I'm just going to use clear sealant where the lens and the housing are joined , and use some PTFE tape on the turn signal bulb threads