In my experience (on both sides of the table), it's okay to say "what are the shortcomings of language_x" if you are interviewing for a specific set of skills.

In my experience (on both sides of the table), it's okay to say "what are the shortcomings of language_x" if you are interviewing for a specific set of skills. If the candidate has a list of languages on their CV, then it may be worth asking the "what's your favorite language" question first.