Most translators have studied the grammar of several different languages. Paradoxically, sometimes we are most out of date with the grammar of our own native language.
We studied it first in elementary school. Again in middle school - but usually skipping what we learned in the earlier grades. By high school, often we were done with grammar, shifting our attention to other linguistic subjects. Unless we continued specializing in our own language at university (perhaps studying to become a teacher), most of us never studied our own grammar again.
Meanwhile we studied the grammar of a foreign language (or more than one). As we studied it later than our own, this knowledge is likely fresher.
Without a conscious effort to keep current formal knowledge of our native language, we increasingly recall grammar notions through the fog of imperfect memory. We should not rely on the grammar book used when we were in grade school, either: grammatical knowledge and consensus change. We should learn what is newly acceptable, what was correct even if our primary school teacher said otherwise forty years ago, and maybe also the rule he clearly explained to the class - but that day we were too busy looking out of the window, and didn't pay attention.
There are plenty of good works available for the Italian translator who wishes to brush up old studies or keep current with new notions.
An excellent little book I've recently read is Luca Serianni's "Prima lezione di grammatica". Although not a comprehensive grammar (such as Serianni's own excellent "Grammatica italiana"), it analyses topics likely to interest the Italian translator, from the plural of unassimilated foreign words ("molti flash" or "molti flashes"?), to problems of coherence and cohesion, and of grammatical accord of number and gender in writing.
The book is well written, but demands some effort - Serianni uses technical terms as necessary, and I had to look some of them up. Some I didn't know, and some I only half recalled from studying grammar so long ago.
Recommended to all Italian translators!