I may be missing something. They make USD by selling bonds, as long as they make more USD then the scheme has running cost they can increase the amount of USD they have right now by selling more bonds below value, leaving any future government in dept.
Venezuela cannot produce USD dollars out of thin air. If their monetary regime allows it, they may print Venezuelan bolivar at the cost of raising inflation in the country.
When we say "Venezuela issues a 2.8 billion USD bond" that means that the central bank sells new bonds denominated in USD on the international market (most likely an auction among bank players in London or NY).
What had happened here is that they did that and then unbeknownst to them one banker sold their bonds to another banker. The act of reselling that debt on the secondary market does not magically increase that debt. It just changes whom you have to repay it to.