@LouisGac & @c_schmitz : i think it's an issue and can be fixed in 3.X : ok for this or not ? Only for develop ?

The fix can be done here : https://github.com/LimeSurvey/LimeSurvey/blob/master/application/helpers/qanda_helper.php#L5666
But need update at all call of this.

I think minimal must be
$oQuestion->attaributes;
array of $answer->attributes
array of $subQuestion-attributes
and array of all core attributes.

1. Current oQuestion with current language
2. oSubquestions with current language
3. oAnswers with current language
4. theme + core attribute with current language (no need to test utf8, for example attribute.other_replace_text directly (this a must have for core too))