Ultimately, 5.5k€ is indeed a good net income, but it still does not match the loan requirement of 650k€. A realistic rate would be above 2000€/month, plus additional costs, and half the income is gone. Actually, one should probably recommend selling the condo. The rental income is nice, but only if it actually comes in. And the TE certainly still pays a loan for it. Better to use the sales proceeds to reduce the loan amount.
But that was not the question at all. Just speculation on how one arrives at a 1% repayment wish.