Is it reasonable for me to expect an official and timely response to my PhD application?
No, final decisions take a while. It is not the fault of the program, but rather an issue of funding. Programs tend to initially reject very few applicants. An applicant that seems weak on "paper" might get accepted if their proposal fits into a very narrow funding scheme that no other applicants are eligible for. There is no global rank order of the applicants, but rather the "best" applicant for each funding scheme is identified. Programs generally construct strategies which lead to the most funding. The strategy is constantly revised when the program finds out about successful/unsuccessful funding applications and whether the applicant accepts the acceptance. Basically the whole system is a nightmare for everyone.