It's difficult to tell from the photo, but the wilted part looks a little greasy/rubbery...? Is that also the remnants of the dead one right in the front on the ground? Did the stem go wiry before it collapsed? It looks that way but it's hard to tell.
So it could be an infection. Or it could be the conditions. Careful with the amount of sunlight -- basil and dill like a lot of sun, but coriander needs shade in the afternoon in 9b, especially if it's summer where you are.

If you have the containers for it, I would take out the healthy ones and grow them in different lighting conditions.

Hello! Thanks for the reply

Yes, the one on the ground is the one that already died. For that one, it did start out exactly like you said. It began in the middle of the stem and looked like it was damaged and bruised before it completely gave out (I'm pretty sure I didn't do anything that would damage the plant though)..

I only have two healthy plants left. Whatever disease it is, spreading fast! Not sure if the affected plants will die since the disease is only on the baby/first leaves. The stems are still healthy on those. However the process on the others felt a little different and started on their baby leaves. And the wilt on them seemed more dried out than greasy/rubbery. The process is kind of like the one with the crumpled leaves in the picture.

I've changed pots and soil for the two healthy ones I have left and moved them away from the window. Definitely going to try that out and see how it goes. Thanks for the advice.

Yeah that sounds like a good idea. So with the wiry stems and the leaf deformities, it looks like damping off to me. Wouldn't use that pot of soil for growing herbs/veggies in again to be safe.

Cilantro is my unicorn... unattainable, I do believe growing cilantro is a myth. They must come from the cilantro fairy, because all of mine bolt immediately after growing 6" tall.

Damping off is what it looks like to me as well.

Miss Moose, have you tried a slow bolt variety? Where are you planting it? Like, how much sun is it getting and what are your high temps when it starts to bolt?