I think it was discovered long before we sent out probes to find out if they were round or not.
Wikipedia (for what that is worth) has the moon being discovered in 1980 from the ground based scope Pic du Midi in France.
So, you aren’t necessarily wrong about being spherical.
On a good night, I have seen 7 of Saturn’s Moons, but, this one is just too small.
Using binoculars?