I think any translation has to be some sort of description rather than the invention of a new catchy name (however good ClimbAloft may be)
According to the very useful link you provided, Accrovoile is the name of a particular piece of equipment (and of course by extension the activity itself)
Fiche technique
L’Accrovoile est un nouvel outil au service de la culture maritime et des spectacles liés au thème de la mer
How about something along the lines of Accrovoile (nautical climbing wall)?
l’ACCROVOILE, un mur d’escalade maritime ouvert aux petits comme aux grands
https://m.facebook.com/events/593259604032161Accrovoile : voguez, grimpez jeunesse !
En tête, l'Accrovoile, ce dispositif ludique qui reprend le principe d'un mur d'escalade, invite les enfants à grimper à huit mètres de hauteur, dans un gréement carré à trois mâts inspiré du Belem.
http://www.rivacom.fr/html2print.php?article=4713English version
Accrovoile, a recreational device which is a fresh twist on the climbing wall by inviting children to climb up eight metres into the rigging of a three-masted vessel inspired by tall ships like the Belem.
http://www.bymnews.com/news/newsDetails.php?id=113090