I have two similar molds
I have two similar molds from Delphi, though the pattern is recessed rather than raised. I filled the recesses with frit, placed two layers of sheet glass over the top, and fused away. They turned out fine. I did not drill holes in the mold. (picture of one: http://www.etsy.com/listing/89256790/fused-glass-plate-with-purple-flowers)
From my perspective the real detail of a mold like that comes from the frit, enamel, or paints you use. The mold itself merely provides some dimension.
I do think it is an unrealistic expectation that you can use a product and then hope to return it because you are unhappy with the results. I’m suspect if you had asked to return the mold before you used it, Delphi would have accepted the return.
Jester’s Baubles Fused Glass Designs