If your ancestor was Jewish, I think you would know it. There are names that are Christian and Jewish.
For the other names that you have, I would recommend posting on Ukraine board. They seem / sound more Ukrainian.
Since the death certificate was written in the states, the spelling is as good as the person's knowledge who was providing the information.It could have been a direct translation from one language to another or written the way it sounded.
The Romanian phone site not to be found at this moment. Can not check out if any Owen or Oven or?? name exist.
As for the Saudi Guera, well the ShtetlSeeker website coming up with a close sounding name of a town in Ukraine to be Sadagura / Sadgera/ Sadgora.One and the same and just a bit North of the city of Cernivci, Ukraine.
Sorry that I can not help much but neither Romanian or Ukrainian is my strong point of much knowledge.