I made sure to "empower" the item (shift right clicking so the item glows) but regardless of whether it's empowered or not, I can't seem to fly. Isn't it just supposed to be point-and-rightclick?
usage context is a Forge server with SpongeForge, 3 plugins, and several other mods installed

It definitely should work that way and did the last time I checked.
Have you charged it with feathers?

Yeah I was just about to say: I took another look and noticed the feather fuel count. The information displayed by JEI didn't say anything about feathers, but your overlay is thankfully intuitive :-)

...if a little ambiguous

@P3pp3rF1y You can close this, though before you do you should probably add a mention of the fuel cost to the JEI info tab.

yup, will keep this open for now and add something in there so that it's clear

okey-doke. Sounds good 😃

Gee, if only there was a way to hold several stacks of feathers in one slot in my inventory 😜