The docs said to use this code to translate a widget :
{% if ( {{uc_lang}} == "fr" ) %}
Rechercher
{% else %}
Search
{% endif %}

but I'v got this error :
Unlimited Elements Error: Error in widget map, A hash key must be a quoted string, a number, a name, or an expression enclosed in parentheses (unexpected token "punctuation" of value "{" in "html" at line 5.

Hi 

It works, thanks !