4when to throw one
Glowsticks cover the places a torch cannot: underwater, down a shaft you are about to drop into, or ahead of you in a corridor you have not walked yet. The bouncy kind keeps rattling around instead of sticking where it lands, which sounds like a downside and is genuinely useful for lighting a room you do not want to walk into blind.
The rainbow version leaves a trail behind the throw, and that trail glows at full brightness in the dark, so one toss draws a visible line down a shaft and shows you the shape of the drop before you commit to it. That alone is worth the swap.
Stock is tied to a Party, so the merchant only carries them while one is running. In the celebration and rainbow secret seeds they turn up in chests instead, taking the place of the plain ones.