By 'complex system' I mean a system of interrogative pronouns which includes more than just 'animate/inanimate' classes of prounouns, like these of 'who' and 'what' in English (e.g. a special interrogatiuve pronoun for each one of Bantu-like classes - if there is such a thing; or gender-specific interrogative pronouns (like 'which one?' having a feminine/masculine/neuter genders in Russian, or French quel(le)? with a close meaning).
Another sub-question is: are person-specific interrogative pronouns possible at all?
Like who+you? / what+we? / when-(s)he, etc. This could be a fairly economical way of a language strategy, but I am not quite sure if that is possible at all in any language. At least, none of the languages I am familiar with has such a feature.