I never tried the cilantro smoothies, but I did use the liquid cilantro drops from Herb Pharm very faithfully for several months. My GD never went completely away, but it did calm down to a large extent. I thought to myself, this cilantro stuff is WORKING, so I kept it up for several more months, but I got no further improvement. I finally stopped taking cilantro altogether and my GD has not flared up with any massive new outbreaks, but I just get single sores occasionally popping up here and there and they could be anywhere on my body from my toes to my neck. I have a lot of science classes in my background, but that was long ago, and I am certainly no scientist now, but my best guess is that how much the cilantro helps each particular person is dependent on what caused the Grover's to emerge in the first place, and that cause could vary from person to person. In my case, I think it might have been way too much sun exposure of many years. For others it could have been exposure to certain chemicals, the Shingrix vaccine, or any number of other things.
At any rate, I'm very sorry to hear about @nodgabnoj and @gardeningjunkie suffering setbacks. I'm still using the CeraVe Itch Relief Moisturizing Cream for my own itching, but I will eventually give that capsaicin cream by Rugby a shot. Thanks and good luck to all!