Dylan acknowledged it here: (Destiny)

by stabbim , Des Moines, IA, USA, Friday, October 05, 2018, 13:58 (2311 days ago) @ TheeChaos

Huh, interesting. I knew it sucked, but I didn't know it was an actual bug.

I guess, to elaborate, because I'm not sure my experience matches up with others: when I first unlocked that tree, I WAS able to get SOME energy back, but only with the absolute briefest possible use. Meaning if I clicked the super buttons, and then hit them again just as quickly as I possible could - so, the shortest super usage that my fingers are capable of - I would get a small amount back. Not much, I'd say maybe 10-15%, just going on memory. Any longer than that, and I got nothing.

I only mention this because the first few comments I read on the Reddit thread made it sound like it literally never gives ANY amount back, and if that had been my experience I probably would have known it was bugged. But my experience was that it technically could happen, it just wasn't anywhere near as effective as I would have hoped.

That being said, I'm glad it's considered a bug, because the current functionality sucks. So much so that I never bothered completing that tree.