There are two possibilities to enter a loan and its repayment into CoinTracking, depending on how you and your country's tax laws see the ownership during the loan.
If you remain the owner of the coins, you can enter a loan as a transfer to the loan place or person: withdrawal from your account, deposit to the other address, entering the name of it into the exchange field. When the loan is repaid, enter a transfer back. Loan interests should always be entered as income.
For this method your coins will stay legally yours, will remain in the FIFO sequence of your purchase pool and thus retain their original cost base.
If you treat the loan as not owning the coins anymore, please enter the loaning out as Spend. This will trigger a capital gains calculation for the difference in value between the purchase of the coin and the spend and the coins will be taken out of your purchase pool. When you get the repayment, enter it as Income. The repaid coins will have a new cost base from the day you received them back.