I don’t think you have a correct understanding of the term “sovereign” as it applies to currency-issuing governments. A debt denominated in Euros is not a sovereign debt to a country like Greece, as its central bank cannot create Euros on demand. As Greece struggles to protect its currency against the demands of bond vigilantes it has little choice but to degrade its domestic economy and maintain some balance in trade at the cost of quality of life for its citizens.

There is no comparison to be made between Greece, or any other nation that adopted a foreign currency peg, and nations that actually have sovereign currencies, such as the US, UK, Japan, etc. Truly sovereign currency-issuing nations can never fail to pay any obligation denominated in the currency their central banks can create at will.

They are also not subject to the whims of bond traders, as the US proved after Moodys downgraded its rating to no effect on the Fed’s ability to set bond prices Japan took on an extreme debt position to weaken its currency after its lost decade. That effort proved less than fruitful for the purpose but did bolster its domestic economy with no risk of default. A “sovereign” currency issuer has no need to even sell debt as a “funding” operation, as it must first create the currency to enable investors to purchase that debt.