It's a "Nah" for me, in English Grigori would have fit better as an old dragon due to his form of speaking, an old dragon that rest in gods-know-where. I found the Japanese Grigori as a intellectual dragon that wants to destroy everything. In the end both did a great job, but i choose Japanese Grigori.
that's just it: Grigori *is* an old dragon. The Dragonforged fought him once and when he got his mortality back he turned to dust. Then Edmund aged to the point of grotesque oldness. Grigori *is* an old fart. XD