How should the faculty's language skills be evaluated?

When I started studying economics as an undergraduate (I had studied history before), I was surprised by the bad language skills of economics professors (in Spanish and Catalan). Some of the best teachers in my centre had translated into Spanish a then famous economics textbook, and the translation was very bad. Both in writing in the blackboard and in speaking, I found that they made constant grammar and other mistakes. However, they were good in many other aspects: they were well organized, communicated efficiently the important concepts, and kept the tension of the students with well structured courses. Yesterday, now myself as an economics faculty member, I attended a meeting with representatives of our evaluating agency. This agency's representatives were accompanied by two foreign professors that were recruited to have an external point of view in the evaluation of the degree of internationalization of our offer. The controversy started when one of these foreign professors asked our opinion about the possibility that we, the faculty, should have our knowledge of the English language tested in a formal exam. The point is that we were trying to demonstrate that we are very internationalized because we now have students coming from all over the world and we teach many courses and entire degrees in English. Our departments now recruit internationally and one of the criteria to recruit new faculty members of course is having published and studied in English and being able to make presentations in this language. Our knowledge of English is also evaluated by the students, who are asked specific questions about this in the questionnaires they have to answer about their courses. A colleague of mine told the anecdote in this meeting that when she was studying her PhD at a famous US university, some of her colleague students complained because they had difficulties understanding an Asian professor speaking in English because his accent was unfamiliar. The direction of the centre told them to adapt to the level (or specific characteristics) of English of this professor, because he was top in the profession. What I mean by this is that yes, I believe that our knowledge of English should be evaluated (by giving a seminar in English when we are initially recruited, by students tests, supervisors' observation or other means), but that we have to be aware that language is not the only important input in good teaching. And that the priority should be to have good teachers in general, which is something multidimensional and with some difficult to measure dimensions (most of them in general positively correlated with a good command of English). I am afraid that many potentially very good faculty members would not feel very attracted by a job offer that included the obligation of passing a formal English test, after having completed a PhD in English, having written in English journal articles and coming from a professional market were basically everything today is in English, which basically is the language with the largest number of bad speakers in the world.