"Who is looking for the cow?"
Translation:Kdo hledá tu krávu?
Would you really ask "Who are looking for the cow?"? It seems that the plural agreement of "who" in standard English requires a specified plural antecedent, not just "who". Say, "Who are those people?"
Same in Czech (except we can drop subject personal pronouns, so your "Who are they?" could become "Kdo jsou?"). Let's enjoy the similarity for once.
Yes, I would ask "Who are". If everyone in the office/home is looking for an item for the boss, mom, dad, and they are told "They are looking for it", one can correctly ask, "Who are (looking for it)?" So ... "Dad, they are looking for the cow!" might be answered with, "Son, they are looking? Who are doing that? who are looking for the cow?" Especially if you are referring to a group or more than one.
But I think the answer I'm looking for is hleda' is singular and hledaji is plural. (In English, "is" is singular, and "are" is plural.)
Closely related is "which": Which is? Which are? Both are acceptable: Which (one) is going? Which (ones) are going? or as you say, just drop the pronouns. ;d