I have looked it up. It is a phytoestrogen and there have been small clinical studies in which it showed promise but more research is needed. There were no mentions of clinical trials to evaluate its promise in ameliorating side effects of antipsychotics but maybe the source I have just read is incomplete.
The obvious question then is: how about progesterone? Are you on Mirena? Skyla?
Prescription HRT consists of a combination of estrogen and progesterone. Estrogen taken alone can be dangerous. To prevent damage to the endometrium, estrogen needs to be counterbalanced by progesterone either via progesterone-only IUDs such as Mirena or Skyla (there is a third one but I forget its name) or orally. Together, estrogen and progesterone can work very well.
So, if this Thai herb is an alternative form of estrogen, where do you get progesterone from to counterbalance the estrogen?
And regarding bone density -estrogen is good for that but you also need weight bearing exercises and a diet rich in calcium and vitamin D. But that you know well, I am sure - aren't you an athlete?