they need to resync the whole grin chain, if they didnt the coins are still on the exchange. if you download grin++ and use your vite wallet login info, you can check how many coins actually exist in your wallet. vite wallets are usable on any grin open source wallet.

so you check the actual balance by taking the login info and using any open source grin wallet, the coins that havent been confirmed yet, might need to be resent from the exchange if not arrived.