I reported this ages ago, too. Still no word on when or if it will be fixed. Either it should take less energy, or at least word the warning correctly, please.
You can also use less energy while gathering fireflies as well. I've spent as little as 10 - 15 energy on filling up a jar. Using 65 energy just happens when the jar doesn't fill, in which case I would love it if there was a progress bar for firefly whistling (just like the other tasks now) where we could cancel once we see that we aren't going to get any fireflies instead of just wasting that energy.
The report you get on how much energy you've used often says 65 when you haven't filled the jar. My energy hit is not 5 at my level so that is definitely not the cause.
I've occasianally spent 5 energy to fill a jar and up to 65 for a half full one, so it varies. I think mood does help too, or so I've heard, but I could be in the best of moods and not gotten a single firefly.
Sorry to point out the obvious, but there have to be at least 7 'flies present in order to fill a bottle. Even if the bottle has a few flies in it they escape and are not available to fill a bottle until the next attempt. That said, the position of the open bottle with respect to the swarm is important. The closer the better, resulting in a shorter capture time. Often jumping and opening the bottle on the down stroke results in the fastest fill time. In the wild you will encounter 'flies that are resistent to capture - the fatter glowing ones.
+1 for Solana's suggestion of a progress bar. I often want to stop collecting when it is obvious the jar is not going to fill, but it just goes on and on using up energy!
Please may we have one of those cute x things at the end of "collecting" or some such, so we can give up if we want to.