Given that I have never heard of add as a French word and that the TLF has no entry for it, I would say that it is indeed an automatic translation failure. It should be ‘faux, ajouter, mot’.

Definitely a Google Translate things. I’ve noticed in many cases before how small punctuation changes cause translation to miserably fail or mysteriously change (parentheses seems to be particularly offending to Google Translate).

On-line free translators are not good, and it’s not just Google translate. There are nowadays some not too bad commercial translation software that possess reasonably satisfying banks of data-memory but little progress has been made on on-line free tools.
The best on-line I would recommend is one that has just been released : the iTranslate4 portal. It is a European project and limited to European languages. I have tested it with various texts (personal and articles from the media) and indeed I have seen a great difference from other existing on-line free tools.

A leaflet with the description of the project.