There's a limitation, it will only show addresses that were previously used by the wallet, you'll likely see the involved (unverified) transactions in the "Transactions" tab anyways.
You can paste their TXID on a multi-coin blockexplorer like blockchair.com to check if where those are valid.

The only reliable way to check the balance is to sync those wallets to their respective networks, because you'll never know if it's an older backup and the wallet was used a few more times after the "Best block at time of backup" of the recovered backup/file.