I’m not sure I understand the caching issue. I’ve used insert_post() followed by both update_post_meta() and update_field() when using acf_form() and I’ve never seen an issue, at least not that I can remember, of the meta not being updated. Where is the page in the codex that this is explained, because I’m interested. Maybe I’ve read it and forgot.
Welcome to the Advanced Custom Fields community forum.
Browse through ideas, snippets of code, questions and answers between fellow ACF users