If Coin98 allows you to backup the wallet using a universal tool, like BIP39 seed phrase, then you are ok!
There are many wallets that give you BIP39 seed phrase, but I would never trust them.
For example, trust wallet is very popular and many people are using it, but I would never use it, because it's close-source and there is no way to know how the keys are generated. Due to the same reason, I would never trust the wallet mentioned by OP.
Thanks for sharing. So what is the safest way to generate keys?