Basically... spell engine wants to use the "use" key, which defaults to right click. But bows/crossbows use the use key/right click to fire. The bow/crossbow firing seems to always take priority over spell casting, even if you enable the "use key priority" option in spell engine. If I change the use key, I can use archery spells via the new key. But then I have to remove "use" from right click, which.. feels incredibly awkward, and kind of a deal breaker.

Is there a way around this? Am I missing something? I'm using the Prominence II [RPG] modpack on a friend's multiplayer server, version 2.5.0 (haven't updated to the latest yet).

Can you name a specific example where this is practically a problem?
It is difficult to find out what you are actually looking for.

I thought it was pretty self explanatory, but my bad. I have a bow and a crossbow. I have an Archery Manual with Power Shot equipped. I'm completely unable to use Power Shot with the bow and crossbow, unless I rebind my use key. Rebinding my use key, makes it so that I am unable to open chests, doors, interact with blocks, etc, with right click anymore. This is very practically, a problem. I feel many players would not want to give up right click interaction.

The ideal fix, would be spell casting taking priority, so that right clicking with a bow uses the spell if it's available, but fires normally if it's on cooldown. Or alternatively, being able to cast archery spells with a different key, without having to change the "use key" key bind, so that I can still use right click to interact with things as normal. But before I made these suggestions, I wanted to ask and make sure I wasn't missing something.

This is a consequence of a technical limitation of how Minecraft internal item use works.
This issue is completely non actionable.