No.
But if they told me that I only had to deposit $6,500 to get that $400 return
That's a 6.15% return.
(and they'd give me credit for the $3,500 difference)
No such thing. You're over thinking the situation.
This is basically how these foreign trades are being conducted today.
Sorry, a 4% coupon is a 4% coupon. If foreign holders sell, because they think it's too low, the return will increase. It hasn't because they aren't selling, yet.
Why do YOU think the U.S. dollar has declined against every other major currency in the last few years?