You do not seem to know what you're talking about. The 12.7bn that was borrowed is going on Twitter's books. Their debt load prior to this leveraged buyout was 5.5bn; it's now 18.3bn[0], with yearly interest payments of roughly 1bn.
1% premium for the risk seems reasonable given that Twitter is not known for making profits. Presumably some of the debt were incurred before the rate hikes so it's kind of on the low side.
This is on top of the principal? They pay 1bn every year and none of it counted against their debt?