There is no way to know because it's closed source, but I'm faaiiirly sure that's how they do it because that's also how the open source Bitcoin Beach Wallet does it (and any LN custodian software who knows what they are doing)
Discussion
The state of the network would look a lot different if sats actually moved between lightning when a WoS user sends 10 sats to another WoS user, right? Like tens of thousands more nodes in existence, so must be just movement on a data table.