HI, I am no expert but have made a few batches of this myself. I know the eggy smell is gas and you need to keep giving it a good shake until all of the gas is out then it will smell like wine.
Mine does not smell nor taste too much of rhubarb, there is a faint taste of it. I have brewed mine fairly low in alcohol 8 or 9% I think so that I have more of a rhubarb taste rather than just alcohol and so that it is light and I can drink more of it. More like a refreshing summer drink rather than something I want to get drunk with.
I made some last year and have only just drunk it. It was the same, not smelling/tasting too rhubarby. A year later it has mellowed a lot and I can taste rhubarb in it. This lot is around 12%.
As for it being green rhubarb, I didnt know you could get it green. Mine was pink.