Astromine and Mythic Metals work fine but your mod - Vanilla Toolsets, - Terran Expansion, Better Nether, BYG and EETM does not.

Also how to disable some of the modifiers? Eg. +10 health points from legendary weapons. For now I changed the amount value for all files in /data/tiered/item_attributes/all/ in the attribute below to zero. Can I just delete this part of the code?

{
      "type": "generic.max_health",
      "modifier": {
        "name": "tiered:rare",
        "operation": "ADDITION",
        "amount": 0
      },
      "optional_equipment_slots": [
        "MAINHAND",
        "FEET",
        "LEGS",
        "CHEST",
        "HEAD"
      ]

Mods need to add their tools to the respective tags inside the fabric namespace (fabric:pickaxes, fabric:chestplates, fabric:shovels, etc.), or you can add the tools to the tags through your own datapack. If you don't want the attribute bonus, you can simply delete it from the attributes list.

Oh and your main GitHub page lacks information about the Tiered mod