Yes, the freezing of external assets in foreign currencies really hurt the Russian economy, so she was not able to pay this debt now. Instead, she will pay this sum in rubles, now this is the only possibility. The United States wanted Russia to be unable to pay its debt and she got it. I think this cannot be called a default, it is rather the repayment of debt with the national currency.
Nope. Freezing of a part of the reserves doesn't take away the capability of Russian government to repay these loans. As I mentioned earlier, they have already made the payment to the Euroclear bank. The payment is stuck at the bank and not from the side of the Russians. Imagine this - you took a loan from your friend. After one month, you made a partial repayment to him through the bank. You made the payment, but it got stuck at the bank due to a technical issue. Will your friend blame you for this trouble? I don't think so.