If you post a link to a preset that doesn't work as it should, I can have a look at it. I am a bit surprised the rank labeling matters much. Of course in the Interactive Diagram the firstRank parameter should be consistent with the lists of square coordinates you give for all the pieces. But if the initial setup looks OK in the Diagram, producing GAME code from it would depend on firstRank only in very few (and non-essential) places. The initial position is defined by FEN, and thus doesn't use any square coordinates. The only info that is encoded as square coordinates in the generated Pre-Game code that I can think of is the location of the castling partners. But even if that would be completely wrong, it just means that you can never castle.
If you post a link to a preset that doesn't work as it should, I can have a look at it. I am a bit surprised the rank labeling matters much. Of course in the Interactive Diagram the firstRank parameter should be consistent with the lists of square coordinates you give for all the pieces. But if the initial setup looks OK in the Diagram, producing GAME code from it would depend on firstRank only in very few (and non-essential) places. The initial position is defined by FEN, and thus doesn't use any square coordinates. The only info that is encoded as square coordinates in the generated Pre-Game code that I can think of is the location of the castling partners. But even if that would be completely wrong, it just means that you can never castle.