I know this is an old topic. If anyone else has a similar question, and I’m assuming that you mean filtering the terms , what would the be filtered by? Terms are already filtered by the taxonomy? I don’t believe that terms have any unique characteristics that could be used to filter them. There is a filter that will allow you to adjust the arguments for get_terms https://www.advancedcustomfields.com/resources/acffieldstaxonomyquery/ I would be careful when using it as the terms in a hierarchical taxonomy could return bad results do to the way the terms are ordered in the selection field.
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