I'm actually glad this thread was revived. I'm still problem-free, but I've learned a few things. I have ultimately decided I do not trust these YURA plugs at all. The new ones have been flawless, but I'm 'losing sleep' doubting them. Ultimately, I decided about two weeks ago that I need to buy a set of NGKs to keep in the glove box, along with a ratchet, extension, spark plug socket, and 10mm. I fear these will leave me on the side of the road somewhere, so I'll have everything needed to swap them on the spot.
Guess what? NGK doesn't make a plug for the 2017-2018 2.0L Elantras. Weird... Only YURA, Bosch, Autolite, and Champion make these plugs. So I initially said "Bosch it is." But I refused to accept that NGK would just skip over one of the most common cars on the road.
So I did some digging. The 1.8L of the previous generation (2013-2016) Elantra is nearly identical to the 2.0L engine in the 2017-2018 (and I think 2019) Elantras, except for the 2017+ having Adkinson cycle and a longer stroke. So I drew the reasonable assumption that the spark plugs are identical, and bought the NGK 9723s (only because I price matched RockAuto at AAP, and only because the entire district didn't have a set of cheaper and superior Ruthenium plugs). I'll swap them in when I get time and see how they perform. I'll report back ASAP.