We are using Taxonomy field ('field_type' => 'checkbox_tree') with MB Frontend Submission to create posts with predefined custom taxonomy values so we have tried to use this filter to set values for taxonomy checkbox tree: rwmb_{$field_id}_field_meta.
The problem with this is that custom taxonomy values are not saved with the post unless checkboxes are manually selected which is the thing we are trying to avoid.
We have managed to achieve this with some JS (triggered change on inputs on ready) but it's not working if checkbox inputs are disabled: 'attributes' => array( 'disabled' => true )...