Learn English – Negative synonym for ambitious

The current buzzword, adopted perhaps to counter the frequent derogation behind 'precocious', is 'gifted':

1. Endowed with great natural ability, intelligence, or talent: a gifted child; a gifted pianist.

[gifted. (n.d.) American Heritage® Dictionary of the English Language, Fifth Edition. (2011). Retrieved January 18 2016 from http://www.thefreedictionary.com/gifted .]

This is not a precise match, as can be seen, because it does not carry the denotation of early maturity that 'precocious' does. That lack may be all to the good: early maturity is a mixed blessing at best.

In my experience, which has involved a lot of reading of British and American literature, as well as being frequently described while growing up as one of them, a precocious child, the use of 'precocious' is balanced between negative and positive connotations, with the scales tipped toward positive.

It seemed to me (note my bias) that the negative connotations arose from (a) a general and despicable confusion with 'precious', and (b) rank envy, which is misplaced. Early maturation in any area (intellectual, emotional, physical) is not often much less always to be envied.

I am not sure because translate and synonym have a different meaning, but maybe the word homologue is what you are looking for. The word can be used to describe something that has the same function as something else in an other system. It is mostly used, I think, in biology. In the context of your question it would mean a word with the same meaning in an other language (so the translation); however, homologue is not a synonym for synonym.