Pointing out language mistakes in a review In one of the reviews I received from a journal on a paper I sent there, there was a complaint that the paper contained a lot of language mistakes, so serious, that they change meaning of phrases. But no examples of such mistakes were provided.

I am not claiming that language in the paper was perfect, though the paper had been reviewed before submission by four different people (PhD's) with a good level of English and also by a native English speaker (not a scientist though). 

I am confused about this quite strong statement about the paper's language despite the reviewer having perfectly understood almost all the ideas in the paper.

Just wondering: is it really typical for reviewers to point out language mistakes in reviews in this way?
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(P.S. Just in case, I am very grateful to the reviewer for his or her very valuable suggestions on other formal mistakes and for giving me some new ideas).
If a reviewer has problems to follow the arguments and feels that this is due to the use of English, they usually include this in the review. Unfortunately, it is sometimes hard to pinpoint exactly what is unclear about the language, but a good reviewer should make some effort to help the authors. On the other hand, if the overall recommendation will be "reject" many reviewers do not invest the time to write down all unclear/wrong/misleading formulations. Note that a good reviewer may still follow your arguments although the language may be quite misleading (by just knowing what you are trying to show and correcting the wording while reading).

So you may ask for clarification (and I find this a reasonable request), but you should not expect to get an answer if the paper has been rejected anyway.