RDHL does not have much market respect so unless it shows Covid results, it is difficult to reach there.
Foreign companies are always somewhat underpriced in comparison with similar US companies with similar/identical parameters. I have noticed these phenomena countless times over the many years i am in the stock market.
Having said that, finally as the saying goes: "Oil will surface over water", namely if the company proves its points(=products) the price gap will be greatly minimised or even equalized.
As you rightly said, RDHL has 3 approved products, plus a potential Covid drug (which so far seems very convincing) therefore a $25 target price is quite realistic in the not so far future.
I agree a good start towards said target price would be with the Covid drug, while bad news will, as you say, cause a sharp price decline.