I would review the written reports. Written documents always supersede oral evidence. (this is not legal advice).
The main reason that buyers sue sellers is for non-disclosure. That means that the seller was aware of materials facts (facts that if the buyer were to be made aware might affect their decision to purchase). The time for discovery I think is three years from the time of discovery to take action, although that time may be different in your area).
The key here is "would the seller have reasonably known that they windows did not operate?" . If the seller writes that "all the windows operate" and they do not, that's a problem. The Realtor's responsibility is to reasonably know about the property condition. If you told them that all the windows needed to be operable, and they did not try each window, I do not know if the Realtor would be responsible. In most cases the Realtor is supposed to be professional but is not held to the same level of knowledge as a building inspector.
The paperwork will probably answer your questions. If in doubt, discuss the your Realtor or perhaps their broker. Did you purchase a home warranty? Some aspects might be covered.