I'd say how the accounts are saved relies on the client implementation, allow me to get Wallet-cli as an example. I'd personally also recommend you employ wallet-cli to produce new accounts. Vanity-ETH are unable to and won't ever keep your private vital. For those who have issues about its trustworthiness, https://manuelsrnje.tblogz.com/not-known-factual-statements-about-enter-your-personal-trx-address-45762527