Is there still a risk that i can lose my btc or bch?
yes because you are using block.io which is a web wallet known to have some troubles in the past and i don't even know if it is trusted or not. and even if it is, you are still using a "web wallet" not cold storage!
and why not just install the bitcoin cash wallet on another computer?
even if you don't have another computer there are still workarounds like using a virtual machine or a linux live on CD or something like that. it is a lot better than using a little known web wallet!