Hey Peter. As you can see from the debate above, people have different positions on the matter. I’m personally ok with using i or b exactly for the type of cases you bring up. Despite being presentational elements, such typesetting has been around us for a long time now and there’s a reason they have been ported to HTML.
I suggest you read the following pages as they present some examples and solutions for different cases (e.g. using i but also adding a class and attribute indicating a word is in a foreign language):