Since, the contract was not designed to handle these tokens, these tokens will be stuck there forever.
ERC Token Standards for Dummies, Like Me
Ayush Tiwari

Great article, Ayush Tiwari, just one question though:

Since Token transfers are done through the Smart Contract that produced them ( & token balances of each account are also stored in the smart contract), what does this mean?

To send some of its money to a new account, an account only calls a function on the Smart Contract (SC1) to change its balances array . The recipient Smart Contract (SC2), which we sent the tokens to, doesn’t have to do anything for SC1 to update balances to include SC2’s new balance.

Is the problem that for SC2 to spend the SC1 tokens it has, it needs to have built-in methods that can call the SC1 functions?