From Daily Writing Tips:
Here are some guidelines for the use of italics with foreign words in an English text.
1. If only one unfamiliar foreign word or brief phrase is being used, italicize it.
2. If an entire sentence or passage of two or more sentences appear in a foreign language, type the passage in plain type and put the passage in quotation marks.
3. If the foreign word is a proper noun, do not italicize it.
4. If you are using two foreign words or phrases, one familiar and one unfamiliar, italicize both of them for consistency and appearance.
5. Common Latin words and abbreviations like etc., et al., and ibid. need not be italicized. An exception is sic, which should be italicized and placed in square brackets.
It would seem you could use italics of foreign words when needed or expected and any overuse -- or not -- will take care of itself. Take care. Vern