Custom fields are not allowed to have special characters like accents. To deploy on several languages a personalized invitation I must add a dear Mr. or dear Mrs. depending on gender and language plus the name of the person. As example in the French language you have Chère Madame (for Dear Mrs) with an accent in the first e. Having no accent will be seeing as misspelled and not seriously. There are names in Spanish that having no accents are misspelled as well. There are other languages like in German having characters like ä, ü and ö.
Could you please arrange that custom fields accept special characters?