There are various reasons why the “Unable to swap these tokens” error may appear.
The most common one is related to liquidity constraints when swapping two (or even one) long tail assets.
If that’s the case we recommend dividing the swap into two swaps using the native token (or any main stablecoin like USDC or USDT) of the input chain as the pivot asset. By doing this it is more likely that there will liquidity to perform the swap.