That's good. Stove enamel is robust. I would remove the offending transfer. If there is a solvent that will take the rest of it up without hurting the enamel, I would use that. You might daub some on the bottom of the tank as a test. If you are fearful of solvents, use a tongue depressor or something wooden to scrape the remnants off. I would mask the area in case you slip and so you can finish it with a high number sanding paper. Then apply the transfer.
You have two choices with modern transfers: water slide or self adhesive vinyl graphic. I have always used the water slides and I have had good luck with them including clear coating over them. However, many painters prefer the vinyl because it does better under clear coat. The vinyl can be thicker than the water slide, but if it is a good supplier it should not be unacceptably thick. I think that I might give the vinyl a go. The VOC Spares will have the water slides. I do not know if they carry vinyl. Classic Transfers does and you can read their tech questions:
http://www.classictransfers.co.uk/
I have purchased transfers from them that the Club does not make and I was very happy with their services.
I take it that the gold line survived?
David