How to order tags on the job submission page

You can modify it slightly. You can use the job_manager_term_select_field_wp_dropdown_categories_args filter to modify the args of wp_dropdown_categories, but it is limited in how you can order it.

From WordPress’ docs:
Field(s) to order terms by. Accepts term fields (‘name’, ‘slug’, ‘term_group’, ‘term_id’, ‘id’, ‘description’), ‘count’ for term taxonomy count, ‘include’ to match the ‘order’ of the $include param, ‘meta_value’, ‘meta_value_num’, the value of $meta_key, the array keys of $meta_query, or ‘none’ to omit the ORDER BY clause. Defaults to ‘name’.

You could create some termmeta to define a custom order, but that is beyond the scope of what we’re able to help with.