acf_form_head() must be called before any output is created on the page. Calling it in your function means that page content has already been generated.
I’m not sure any of the other stuff you’re doing will work either. ACF does all of that initialization when you call acf_form_head() and like I said, this must be called before html output is started.
https://www.advancedcustomfields.com/resources/acf_form_head/
