Is 'kind' an imaginary concept, that we can define it according to our desires, or is 'kind' real, that we can only describe it?
I think this is a very important question that everyone should look into to move the conversation forward. Even if we look at taxonomy used by the majority of scientists, beyond the species level it is all for our convenience. What we classify as a mammal, for instance, has no bearing on anything in the natural world. What nature cares about is if it can produce fertile offspring to pass on the genes, this would be the species level.
If we say species equals "kind", this puts YEC in quite a dilemma, IMHO. This means that asserting that kinds are fixed, we should see no speciation, yet we do. In addition there are thousands upon thousands of species that cannot survive a global flood without the help of Noah's Ark. So with that definition of "kind", are YECs willing to claim that Noah had 9,000+ species of ants? I think there are around 11,000 species of bats and so on.
However, many YECs claim that several species derived from one species from the ark. This is speciation; the act of making new species. So it only makes sense that "kind" does not equate to species. This means that "kind" would be the same level of realness as scientists making up different taxonomic levels, i.e. family, class, order. But, scientists can put each animal in a specific class, order, family ect. through objective and observable traits. Like mammals have hair, birds have feathers, and we have a clear definition of the traits we look at.
So while I think that 'kind' must be above the species level, forcing it to be 'imaginary', we need a clear definition of kind that is objective and both YECs and non-YECs can look at the same set of animals and come to the same conclusion because it is objective.
As of right now I have not seen a clear, concise, objective definition of kind. As creationists are the only ones who claim that there are kinds, the burden is on them to come up with a good definition, IMO. Without a good definition, I doubt that any real conversation can be done on the actual evidence nature has provided us with.