I think writing would be worse, especially in case of communication issues, since it would hide the misunderstanding. In that case I would start by explaining

I think writing would be worse, especially in case of communication issues, since it would hide the misunderstanding. In that case I would start by explaining very clearly that is the intensity of the words to be used, whether they express low/medium/high scale. And I would also explain even more clearly what's the level of intensity for me, so that the person understands what is at stake. In fact, I do it even with native speakers, clarity is godsend.