Inter were trailing 1-0 in Sicily when Esteban Cambiasso struck twice in quick succession.
"We struggled a great deal in the first half and Catania were well placed. The second was different and the substitutions made us more vivacious," said Leonardo.
"We proved that we have great character, as such a comeback is extraordinary. These were three crucial points to keep pushing forward.
"This side has many resources and the spirit they have always had. The team is accustomed to fighting for a result."