Custom sort order

I’d like to be able to specify a custom order for my CPT-onomies

As a simple example, if I created a CPT-onomy for days of the week, I’d like to be able to order them Sunday, Monday Tuesday, etc… (as opposed to date or name order).

I’m currently getting my terms like so:
$days = wp_get_object_terms($post->ID, 'days', array("fields" => "all"));

The entry for wp_get_object_terms() suggests that term_order can be supplied as a sort field. There is a term_order field in the wp_terms table, which presumably I could hook into and set my custom order using a plugin. I could then call wp_get_object_terms like this:

$days = wp_get_object_terms($post->ID, 'days', array("fields" => "all", "orderby"=>"term_order", "order"=>"ASC"));

However, because the taxonomies created by CPT-onomies seem to be created on-the-fly (i.e. aren’t stored in the wp_terms table), this method won’t work. Does anyone have any suggestions as to how I could make this happen?

Cheers

https://www.ads-software.com/plugins/cpt-onomies/