Unfortunately this doesn’t actually seem solve it when I test it out.
If you create a field group settings, add a field to it my_settings, when saving via the UI you get a wp_postmeta of settings_my_settings with a field key like field_59c383916102a.
If you create it programatically via your recommendation:
update_field( 'field_59c383916102a', $some_html, $some_new_post_id );
In the database you instead get my_settings (when settings_my_settings is needed). This causes then field to be empty when then opening it up in the UI.
