Versions (Be specific, do not write "latest"):

• Enigmatic Legacy: 2.10.2
• Curios API: 1.16.4-4.0.3.3
• Patchouli: 1.16.4-48
• Forge: 1.16.4 - 35.1.28
• SpartanWeaponry: 1.16.4-2.1.0-beta-1
• Apotheosis: 1.16.3-4.4.1

Description of a Bug:

Spartan weaponry add new type of crossbow called 'Heavy crossbow' (H.C.). Unlike vanilla crossbow, these H.C. use its own type of ammunition (Bolts) and require 2 steps before it can shoot things. First is to load a bolt (charge), and second is to aim (charge) (reduce dispersion).
The bug happened when you enchant H.C. with 'ceaseless', 'sharpshooter' or both. The H.C. with enchantments now can only load a bolt but can no longer aim (The H.C. will fire instantly like vanilla crossbow) and the bolt fired will be converted to vanilla arrow. And if I am correct, the damage won't increase either if you enchant it with sharpshooter.

Next is 'Crescendo of Bolts'. This enchantment is from mod Apotheosis. It allows crossbow to fire additional times without consuming any arrow and already charged (Like adding a free magazine to a crossbow and you can shoot with it until the magazine run out). It have default maximum level of 3.
Like the previous one, the bug happened when you enchant vanilla crossbow with 'Crescendo of Bolts' and 'ceaseless' or 'sharpshooter', or both. The 'Crescendo of Bolts' will no longer function. However, unlike previous case with H.C., if sharpshooter is applied, the damage is increased as intended.

In this case, my speculation would be that enchantments from this mod enforce vanilla behavior on the weapons (in this case is crossbow), causing additional functionalities to no longer function as intended.

How to Reproduce:

1. Acquire the weapon you want to test (Heavy crossbow or vanilla crossbow with 'Crescendo of Bolts' enchantment)
2. Enchant it with 'ceaseless', 'sharpshooter' or both
3. Attempt to shoot with it..
4. Behold!

Logs:

No any relevant information found in .log files ~