Maybe QF’s seat maps are outdated?
But I’m still not sure of what you’re trying to work out, based on your description.
That map I linked has 6E & 6F, 7E & 7F, and 8E & 8F. These are all middle seats, next to each other. There’s something in between the 6 row & the 7 row, people who know more than I will know what it is, it looks like a galley or maybe one or those self-serve bars for customers. The seat-choosing map might not show whatever this dividing item is.
That map shows no row 6 or row 8 window seats, only row 7 …. 7A and 7K. It also says 7A is not allocated on long-distance domestic or international flights (not sure what “long distance” means - Singapore is “medium haul” by some definitions I think). There’s also a 5A, which is next to 6E; which they claim isn’t allocated on long-distance flights.
The two other maps show a full row 6 & a full row 7 … window and centre seats, 4 across for both, A & E & F & K.