Alright, ripple checked the mod. It's crystal is spawning just fine! Looks like you'll just need an extra hint! After going left of the temple, use your ibek to climb up the mountain. Then throw yourself into the chasm below!

Hey, sorry that the hint isn't good enough lol. I'll tripple check when I get home to make sure the crystal is spawning properly. Until then, check specifically due west of the Poseidon temple.

I haven't been able to find the fireflyer crystal. Looked all over the Poseidon temple area