I'm not the maintainer but I think a better way to implement this is to have the source package goldendict-ng provide the transitional package, possibly with a dh_gencontrol hack to keep the version number of the transitional package "low".
Boyuan Yang, since you were until very recently the maintainer for goldendict and because goldendict-ng is orphaned, would you like to make this change? Thank you, Jeremy Bícha
