I just added the modern-in-medieval tag to How would a person with modern knowledge of chemistry and medicine fare in Ancient times?
However, the question clearly states that he is interested in modern science set in a time before medieval. It's not exactly modern individual, just their tech, and it's not limited to medieval times.
I feel the spirit of the tag still applies to the question, but not the literal definition. It may be worth making the tag a more general concept to include these sort of questions. At the very least I think the tag should not be limited to medieval times, modern-in-past or something along that lines generalizes the tag so it can be applied in other situations.
As an example I would like to be able to tag my question here: What would be the impact of a modern programmer and laptop being dropped into World War II, possibly breaking Enigma?
This isn't asking about medieval times, but the idea of modern traveler going to the past still applies, it feels like something closely linked conceptually to the other questions that have the tag, it's a shame that no one can find this question if their interested in other time traveler in the past style stories and click the modern-to-medieval tag (after all this is such a perfect question, having been written so perfectly by a man who is clearly smart, ingenious, and above all the humblest man ever to live).