Have anti freeze leaking from back side of engine?

Hello,

Coolant leaking from the back of the engine could be due to a heater hose leak.
One of the common places the leak happens is the heater core hose, which goes to the fire wall.

There is also a coolant bypass hose at the back of the engine. Those tend to leak at the base, where it connects to the engine.

The best course of action would be to inspect and verify what is leaking.
Please note that without actually looking at the leak it is nearly impossible to say exactly what is leaking.

Take a look at this helpful guide:

https://www.2carpros.com/articles/car-is-leaking-coolant

Please let me know if you have any questions.
Thank you.