I hope your M-i-L gets better soon. Such a difficult thing to cope with.
No experience of it but if it is an effective medicine you would expect it to be available here. Providing care for people who have had strokes is difficult and very expensive so if there were a fix, the NHS would be pushing it.
This is not available here, which suggests it may not be effective. A lot of strokes steadily improve over time, thank goodness, so bear this in mind if you hear stories about how this or that "made all the difference" to one individual somewhere, when the healing effect of time passing may well have been the key factor.
I suspect these herbs are not going to be free of charge and you will have no idea of exactly what is in them. A lot of "herbal" remedies include heavy metals like lead or arsenic (though they are natural enough) and can be poisonous to nerves and brain.