I would guess that the type of grammatical errors depend a lot on the mother tongue of the author though, e.g. one can see German, French, Spanish, etc... shine

I would guess that the type of grammatical errors depend a lot on the mother tongue of the author though, e.g. one can see German, French, Spanish, etc... shine through in an English text by the types of errors, for instance as a German I like to write overly long sentences, split by commas. ;)