Did you try ChatGPT? It may also assist you in the matching.
As a visual helper, you could also chart the 1K tags as embeddings in a 2D graph [1]
My setup when manually working on this is a split-screen outliner (filter, drag&drop...).
Once the taxonomy is done, I assume you will not be able to reflect those levels back in pocket ? I just see a flat list of tags there.
[1] https://cookbook.openai.com/examples/visualizing_embeddings_...