The effectiveness of nootrop for ordinary people is a myth. They are used for the mentally ill and mentally retarded, and it really helps them a little.
I wouldn't. Learning a language is a long process, which clearly does not fit well with a variety of stimulants. Although they give an increase in working capacity / mental abilities, then there is always a "rollback" and depletion of the body's forces. Any person who at least once drank coffee felt this on himself, especially if he drank it regularly. So with all the stimulants, you will lose more. than you will find.
Brain stimulants? What? Why? The question is rather strange, at least for me. Overall, it's worth noting that these stimulants generally provide very, very little, if any, actual benefit. Besides, before they somehow learned 5 languages without stimulants, right? Stimulants are needed in sports, but not in learning another language. Absurd. Besides, the most "effective stimulants" are drugs, but how can drugs help you learn a foreign language? Unless they will give an increase in strength. Well, or coffee can also be attributed to stimulants, but without it, you can learn another language. Conclusion: Stimulants are not needed. IMHO