Is one excused for being completely ignorant of the rulings concerning allusive divorce with the intention of its occurrence, especially after saying "خلاص" (that's it/enough) in English to his wife, along with the possibility of an intention to separate?

A kinaya divorce does not take effect if it was not intended, and doubt about the intention is not considered. The default is the continuation of the marriage, so divorce does not occur with doubt. One must turn away from obsessive thoughts and seek Allah's help.