There is certainly much they could do to expand their African collection, I believe displaying just 2 Zebra for their African Savanna is not really cutting the mustard. Even without importing, some Baboons could be added in a new rocky exhibit that would be both entertaining and interesting, Both Hyenas and Painted dogs could be obtained without to much trouble as well. I believe having even a trio of Lions would be very popular with the public and also been asked for on the social media.
Some species of antelope could be added to the current Giraffe/Rhino enclosures with out the need to build any new exhibits or even import them, Oryx, Addax and Nyala also Eland could be obtained to add interest and a better display for the public. Even a couple of Ostrich could be added without a major cost they certainly have enough off display room to operate a nice verity if they so wished.