You said latest huh? Well, there are reports of a scattered African Romance-speaking communities in the interior of Algeria in the Early 18th Century, so my throw would be a lasting spanish presence in North Africa during the overturns of the 16th Century (where the spanish and the ottomans subsequently and frequently captured Algiers and Tunis from each other), resulting in the remnants of the African Romance community being able to put its things together after the spanish authorities found about them, the pretty catholic spanish would be dazzled by the propaganda value of finding a african romance community that continues with its christian religion after, well, everything. It most probably would be well documented enough after that, and could result in a revival with possible local converts to christianity (because well, spanish rule) adopting it as well to detach themselves from the spanish. The problem is, there's a considerable chance that after this possible revival during spanish rule, the spanish are violently put out and the african romance community (including aforementioned converts) seen as fifth-columnists by the muslims, what can result in possible expelling, genocide or anything like that, if spanish rule is thrown out by the ottomans i find less likely reprisals against the community and thus less likely for the community to fade away after the spanish-rule revival.
