From Empower Playground's website it seems that the merry-go-round doesn't directly charge the lanterns it charges a battery underground:
"The electricity generated by the merry-go-round and all other play equipment in the EPI system is carried by underground wires to a power enclosure, created by Goal Zero, where it is converted to direct current and used to charge a large AGM deep cycle battery (much like those found in golf carts). In the enclosre, a state-of-the-art MPPT (maximum power point tracking) power controller effectively manages the charging and discharging of the storage batteries, protecting against drainage and ensuring long battery life."
Play Pumps gifted their technology to Water For People. You can see a full update on their website: