I do not think that there is any way to do this. With load terms on ACF gets the terms in the order that WP returns them in the order WP orders them. With Save terms on nothing is saved that would tell you what order they are in.
I don’t know if this will work. What I would try is to not use not use the ACF save and load terms feature and instead create my own filters that would do the loading and saving of terms (get_terms and set_terms). If you do this then the value returned by ACF will be in the order that the terms were selected and you may be able to use this to somehow order the terms. With save terms/load terms off ACF saves an array of term IDs in the DB in the order selected. With them on this value is not saved or loaded and any call to get_field() ignores the value in the DB even if it is there.
