hyperforeignism

The use of a sound or form that is perceived as foreign in a context where a native sound or form would be more correct based on the original language of a given loanword.

When he wrote that he was going to “Hämbürg”, this was considered hyperforeignism because the German form is “Hamburg”.

For example, there is an awareness based on French that /dʒ/ is an English-type consonant, for which /ʒ/ is the ‘foreign’ equivalent. But when this leads to raj, Taj Mahal, mah-jongg, or adagio with /ʒ/ instead of /dʒ/ (although the languages of origin have affricates in these words), we have what might well be called a hyperforeignism. [boldfaced in source]

The misapplication of foreign pronunciation or usage more broadly; approximation that is misapprehensive or pedantic; use of a foreign form that is not in common use.

When she talked about the beautiful “freschi”, this was considered hyperforeignism because in English one says “frescoes”.