Enormous effort was expended by them - something not fully understood by current EU members - to accomplish their domestic transformations and so adapt themselves to the incredibly extensive acquis of the Union.
Realizaron un esfuerzo enorme -algo que los actuales miembros de la UE no entienden por completo- para lograr esas transformaciones domésticas y así adaptarse a los increíblemente extensos requerimentos de la Unión.