What do you mean by debt leverage? I don't really see how you can have interest without allowing for borrowers to profit from that debt. Businesses use debt to finance their operations. I can get a mortgage and profit off the appreciation of my property.
I had never heard of that contractum trinius thing! But it really doesn't seem any different. The borrow has to pay insurance premiums to the lender instead of interest premiums. Its only different in name. Additionally, the borrow has to pay for a separate contract that will allow them to profit off the debt! That's debt leverage for you!
You're correct, they're just thinking they found loopholes around the issue. Islamic texts explicitly call out this behavior and prohibits it. You can't stitch together individual legal contracts to reach the goal of lending money with interest. You can't "kid" God.
I had never heard of that contractum trinius thing! But it really doesn't seem any different. The borrow has to pay insurance premiums to the lender instead of interest premiums. Its only different in name. Additionally, the borrow has to pay for a separate contract that will allow them to profit off the debt! That's debt leverage for you!