Radio is fine and dandy to communicate across long distances and electric communication can let you speak privately, but the ability to produce and interpret sound is a bit too dynamic for me to believe your creatures have absolutely zero uses for it.
Starting with navigation and predation: Dolphins aren't blind, and neither are bats, however, they both have the ability to echolocate regardless. Dolphins use it to hunt in murky darker waters without problem, and bats can use theirs to find prey and navigate in 3 dimensions across complex environments in complete darkness where there's just not enough light for their eyes to work with (funny and tragic enough, a problem regarding bats is that they give more credit to their vision than to their echolocation, which is why it's still possible for a bat to hit a glass window even though it could "hear" it was there).
And before you think it's something only highly specialize mammals can do, oilbirds also use it to navigate the dark caves they roost in. So right off the "bat" we can already see how having eyes, unlike what you might think, doesn't make echolocation pointless.
When it comes to hunting, even animals with great eyesight and no echolocation ability can use sound to their advantage. Many owls, in addition to their superb night vision and great eyesight, also make a fair use of sound to hunt, especially in snowy regions where their prey can stay hidden within the snow. The asymmetrical ears and facial disks in some of these owls also ensure they can perfectly hear the smallest sound in 3 dimensions, accurately determining where their prey is without being able to see it. This shows well how even the ability to hear well is already a big advantage even if you can't use it to "see" the world around you.
"but surely sound becomes pointless with radio communication right?" well remember how your animals can communicate privately with electric fields? Elephants also have their own private channel, except it still works between individuals several kilometers away because instead of electric fields elephants can communicate through infrasound. Even if radio waves can travel further, not every single creature around can understand or even hear certain low frequencies, seen as how humans can't even hear these frequencies (which is precisely why we're call it infrasound, being lower than the lowest frequency we can perceive with our ears). Certain crocodilians also use similar frequencies to attract mates, propagating then through the air and water in a call which humans can barely perceive with their ears (although the intense ripples they create in the surface of the water are visible). It's not crazy that in your world many animals use radio frequencies to communicate, since we have that with ordinary sound. Similarly, it's not crazy that some of your creatures don't have the same auditory range, meaning that while species A needs to rely on touching one another to talk privately, 2 individuals from species B can maintain a conversation kilometers away knowing no one can understand or, at times, even hear them (think of it as a group of coded messages, it's both the frequencies and language used that needs to be understood in order to crack the code, except not everyone can even perceive the frequencies to begin with).
Lastly: getting funky. I already mentioned how crocodilians have low frequency mating calls, but they're not alone. Whales, birds, dolphins and other animals also engage in singing to attract a mate, with birds also mixing in things like flashy displays, impressive nest buildings, gifts, dances and more. They lyre bird particularly can crank up singing to the next level and mimic a number of different sounds it hears, given enough time, with some learning to mimic sounds more common to human environments such as chainsaws and construction tool, as well as the sounds and calls emmited by different birds (supposedly being so good at it that even the mimicked animals themselves would believe to be hearing another of its own species).
I'd also add how the ability to mimic sounds can also be useful for defense, but given you said most of your creatures use radio frequencies rather than sounds, I'd suppose there wouldn't be all that many sounds useful enough for mimicking to be that big of an advantage.
So summing up, even if you have other means of communication, the ability to perceive and produce sound is still very useful, from being able to navigate in dark places where light is either absent or mostly useless (fog, murky dark waters, underground cave systems) to being Able to hear relatively silent prey scurrying around unseen to communicating privately across vast distances without using a system everyone else understands and uses. It might no longer be the best for animals that are in a calm situation and close by, but it's still got uses for navigation and for communication, especially if you're hunting a species that went through that logic and has little to no ability to perceive the sounds you're using, meaning your ability to hunt in packs remains unaffected and completely secret (until natural selection starts to do its thing, that is).
