The item ids for the new (experimental) pottery shard items have the descriptor (the shard type) after "pottery_shard" - for example, pottery_shard_archer.

This is inconsistent with most other items in the game, for example the new (also experimental) armor trim smithing templates (e.g. vex_armor_trim_smithing_template), spawn eggs (e.g. pig_spawn_egg), and all other blocks/items with colours or materials in their ids (blue_banner, oak_sign, chest_minecart, etc.).

Given these precedents, the correct name for pottery_shard_archer should be archer_pottery_shard, and likewise for the other pottery shards.