Agree you can really only spot the jackals properly from the train. It's also often true that you get a much better look at the wolves from the train as well and can certainly appreciate the size of their enclosure better from it.
You can get to the Geladas 2 ways. Firstly, by walking behind the new Meerkat enclosure, or alternatively, by approaching via the 'wobbly bridge' which takes you over the top of the lemurs. If you don't know already, this is accessed from the corridor with the anteaters on one side, and Sasha on the other, with the otters & silverleaf monkeys also right near its entrance.