get_field_args unable to overwrite attributes

Using cmb2 on front-end to create a new post submission form.

I build the form, then based on the $_POST values I change the classes, description etc… to the field before showing the form.
The problem come by using get_field_args after the fields have been created.

I’m unable to overwrite the attributes array because of array_merge that take the original metabox fields as secondary parameter.

https://ww.wp.xz.cn/plugins/cmb2/