I'd advise against using multi-coin wallets for your bitcoins, generally speaking they are less reviewed (most of them are not that old) and are slightly riskier even if they are completely open source. It is best to stick to the known wallets that are very old and trustworthy such as Electrum, Bitcoin Core, etc. to store your bitcoins and only use the multi-coin wallet for your altcoins.
I practice the same.
With Bitcoin, I store my bitcoins in wallets for Bitcoin only and it's recommended to verify wallets too.
[Guide] How to Safely Download and Verify Electrum.The paranoid user's security guide for using Electrum safely.[Guide] Verify Bitcoin Core wallet.With altcoins, I store them in other wallets that are for altcoins only and even they are multicoin wallets that support Bitcoin, I will never store my bitcoins in those multicoin wallets.
I see multicoin wallets are less safe than Bitcoin-only wallets and such wallets have only existed recent years while years ago, there are no multicoin wallets with support for Bitcoin. This contains a risk you said, these multicoin wallets are too young to fully verify about their security quality so to be safe, avoid storing bitcoins with such wallets.
Bitcoin transactions are irreversible so be more careful is the best practice.