And doesn't this promote centralisation, if everyone uses this asset for their transactions?
The way we are designing this, anyone should be able to issue a hybrid asset on the network. This means users can practically create gateways between currencies, while transactions on those gateways are governed by node-swarms on the network.
Does 'a decentralized system of many nodes' also mean that the risks of the system failing or somehow losing money because of a lengthy transfer time are minimized?
Yes. Like with Bitcoin, Ethereum and other cryptocurrencies, the network has a failover mechanism. This means a transaction can be picked up by other members of a swarm in case of node failure, and incomplete transactions can be canceled (for negligible network fees).