The ETH wallet API does not import any internal transactions as stated on the import page, but deposits and withdrawals are.
Therefore you need to add the following additional transactions to correctly mirror the swap in CT.
Withdrawal coin1 from ETH Wallet (imported through ETH wallet API)
Deposit coin1 to "exchange" atomic swap
Trade coin1 into coin2
Withdrawal coin2 from "exchange" atomic swap
Deposit coin2 into ETH Wallet (imported through ETH wallet API)