It is indeed a eulogy for R' Zalman Katz of Mantua. It is not surprising to me that it does not contain biographical information, as the original purpose of a eulogy was to commemorate the good deeds of the deceased in a way that inspires others--not like eulogies today that sound like dinner testimonials.
An interesting side note: The caption says that the eulogy was delivered in the courtyard of the synagogue, because the synagogue was locked down due to a plague. Sounds eerily familiar.
