Oh yes, I like this. You're right, there are so many. I have to introduce you to some you may not know. Catman, when he was cancelled, continued in Australia but Kitten became Kit. The Night Hawk (the British one) had a junior version, wings and all, Sparrowhawk, real name, Snub Hawkins. Billy the Cat had his cousin, Katie, in similar costume as well, more a companion than a sidekick. (One of my favourite costumed heroes)
But, as for The Terror, it wouldn't have mattered to me if Tim had been called, The Beige Dumpling, they are just too good and those cossies are so brilliant. The ones you mention, Magno etc., it seems the big guy has a codename but they couldn't be bothered thinking one up for the wee guy. I've always liked the sound of, The Crimson Avenger and Wing.
Got to look up some more