This is a common complaint in our Zoos- that staff are often hard to find when one wants to ask questions. Exactly the same issue has just been raised on the Dublin threads and it seems almost universal. Obviously no zoo can afford to have staff hanging around just to answer questions so they are understandably usually fully busy, and so may not be in evidence. But it also means visitors who would like to raise specific questions or concerns often aren't able to, which may work against the Zoo in the long run.
Posting notices about behavioural problems would, in the absence of staff to ask firsthand, help a lot more in allevaiting the problem you mention of people leaving with false or bad impressions of what they have seen at the zoo. It is done sometimes- usually in the case of e.g. an obvious injury or an example of extreme stereotyped/repetitive behaviour but it could be employed more often- though zoos may be understandably reluctant to cover their exhibits with such notices!
Perhaps the Zoos should take note and post the notices if this is a common complaint. It is very obvious when an animal such as the leopard in this case displays behaviour that is upsetting (due to education now people do know more and will do doubt have heard that pacing is generally a sign of stress of some description) and for the many people that do complain there may be many more that think it but don't say, only talk amongst themelves/friends/family re their experiences.
I did think about the fact that notices highlighting problems doesn't sound like a good idea as it may well highlight the problem to those who didn't notice in the first place but then I imagine if they didn't notice, they probably weren't paying attention anyway and therefore would be unlikely to be reading the notices