Mobians can understand the language of flickies and critters and other non-anthropomorphic animals. It's been shown in canon multiple times.
Humans, on the other hand, do not know the language of ferals in the slightest.
Now then, watch this.
Taking a two second joke clip from Sonic 2 movie and the multiple interactions between Sonic & any other earth animal, I deduce that the same applies on Mobians in the SCU verse.
(It also explains how Sonic communicates with Ozzie and perfectly manages to convince him to play along with his silly games and everything. And I also believe he understood that turtle)
So the Wachowski brothers can speak to animals and it's both baffling to their parents and helpful when Maddie has a pet or animal come in which is too hurt or uncooperative and whatnot, and it allows the three brothers to involve woodland creatures into their shenanigans and pranks.
April 1st is a nightmare in the Wachowski household. And so is October 31st.