I am currently a PhD student in theoretical computer science applying for postdoc positions in Europe and the US that will start next year. Apart from my advisor's, I will also include a letter of recommendation (LOR) from a professor with whom I have published several articles. The problem is that while he is an accomplished researcher in his field and let me know that he thinks highly of me, his command of the English language outside the scientific realm shows some major flaws and I have reason to expect that this will also reflect in an LOR. Now I am worried that this will affect any impression the LOR will make towards the negative.
Is this justified? How likely is it that an otherwise excellent LOR will be viewed negatively by a selection committee because of bad grammar/clumsy expressions?
Edit: A good answer for the US has been given, but I am also curious how it differs from Europe.