...how long claw-toed frogs live, please?

Twelve years ago, a friend asked me to take over the care of his three African claw-toed frogs, as due to illness he could no longer manage them. To the best of my knowledge, he had had them at that point around eight years, and he was fairly sure that they were at least three-four years old when he got them.

One of them died in 2005, but the other two are still going strong. I'm more into dogs than frogs, tbh, but I've grown kinda fond of them over the years, and I'm quite happy to just go on taking care of them...but by my reckoning they are now 24! Is this normal???

They still seem perfectly healthy, they both vocalise, eat properly, and will come to the surface to feed, or catch my finger, when I come to the tank, but I can't truthfully say they've really had much attention, they've just kinda "sat there" for 12 years! (tho recently one of them seems to have taken to clicking along to one of the songs I play regularly, tho I appreciate I could be imaging things!)

Thanks for any help
Tess