Or is this not how Adaptogens work.
This. Nothing that crosses the BBB promotes homeostasis, unless it is to counter the effect or aftermath of another drug. The entire concept of a plant extract, with dozens of alkaloids with varying and sometimes contradictory effects, inducing homeostasis is almost laughable and is something you probably would see on some homeopathic website.
Taking it with noopept should not lessen the effects, especially based on your theory. Theoretically, because the mechanism of action of Siberian ginseng is poorly established (at least on what if any NT its alkaloids it bind to), it could act on glutaminergic or cholinergic pathways which could lessen or enhance noopepts effects. However, this theoretical scenario is extremely unlikely.
So if you took a substance such as Ritalin or omega 3 that significantly increases dopamine levels. Taking Siberian Ginseng along with ritalin /omega 3 would lower these dopamine levels back to baseline.
I have not seen anything to indicate that fish oil significantly increases dopamine levels. Methylphenidate (Ritalin), will actually lower the density of dopamine receptors, effectively lowering dopamine levels.
http://www.ncbi.nlm....pubmed/12776228
Even if there was a marked increase in dopamine from either of these substances, Siberian ginseng shouldn't really do anything to "lower" the dopamine levels. There is no substance on earth, that reverts every single neurotansmitter back to baseline simply because it is marketed as a "homeostasis promoter".