In v1.20.1 Minecraft, using v4.0.9 of the Primal Magick mod, the shackles do not seem to block attunement effects.

Steps to reproduce:

1. Craft shackles for the various attunements, and activate them.
2. Craft a lot of mana salt.
3. Note the visual effect of increased speed, just standing at the crafting table. Also note that swim speed is affected.

In the game I'm currently playing, I've finished "Master" level of the various schools of magic, so I've got a moderate "permanent" attunement level in most of the magic types. It doesn't take much "temporary" attunement to push me into "lesser" territory. Crafting is sufficient to trigger the effects, even with the shackles all "active"; but casting the shearing spell will also activate it. (I haven't tried a lot of the other spells yet in this playthrough.)

I'd maybe recommend:

• when the shackles are activated, set any accumulated temporary attunements to zero;
• when the shackles are active, prevent any temporary attunements from accumulating;
• immediately end any attunement effects when the shackles are active;
• prevent any attunement effects from being applied to the player when the shackles are active.