Hi MitsuWa,
You're right, this is indeed not a traditionnal African techniques, but a restorer technique. Gelatin glue (along with starch and hide glue) is prefered in museums, as it is easily reversible, and will not damage the object while degrading over time, contrarily to most modern glues.
I found the gelatin glue technique (and the garlic tip) to bond metal to wood on a furniture restorer website, that had experience working on pieces in the style of Boulle, which include a lot of metallic ornaments that tend to come loose easily.
I guess that pitch glue could have been more accurate (even though I'm not sure, as I wasn't able to see any remnants of the original glue), but since I'm not a professionnal restorer - I actually learned a lot while doing this restoration - I prefer to use reversible techniques. (And if professionnal restorers use gelatin glue for metal ornaments on wood, I guess it means it's sturdy enough, only time will tell !
)
Battara,
I would love to get some Tuareg jewelry too (I guess it could be found in France), but I need to learn about it first, as I wouldn't be able to recognize a traditionnal piece at the moment !