The advancement "Who Is Cutting Onions?" has a capital I in Is while other small words in titles are lower case. For example "the" in "Bring Home the Beacon".
The word "the" is lowercased because it's an article, but "is" is a verb, so it's too important to overlook (like its opposite "isn't"). Also, your example suggests words like "it", "can", "you", and "me" should also be lowercased, but those all carry important meaning(s). A word being short doesn't mean it must be lowercased in a title.
However, I'd prefer "Who's Cutting Onions?" as the advancement's name because it flows better.
The word "the" is lowercased because it's an article, but "is" is a verb, so it's too important to overlook (like its opposite "isn't"). Also, your example suggests words like "it", "can", "you", and "me" should also be lowercased, but those all carry important meaning(s). A word being short doesn't mean it must be lowercased in a title.
However, I'd prefer "Who's Cutting Onions?" as the advancement's name because it flows better.