I didn't explain myself very well. I didn't use the Rev1 firmware that comes packaged with QMK. I built my own QMK firmware using kbfirmware.com. Like you, I thought that I had simply assigned the keys to the wrong pins on the microcrontroller, meaning that I had a software issue. However, after a lot of troubleshooting, I opened up the schematic and board on EasyEda, and I think there is a mistake in the matrix.
I'm referring to the switch physically positioned between S101 and S102 on the board. On the schematic, it's called "6.25u Space." I'll call it S101.5. S101.5's row pin is wired in parallel to S101 and S102. However, it's column pin is connected by a copper trace to S83, meaning that its position in the matrix is exactly the same as the right bracket key (S51): row 7, column 5 in the schematic. On the PCB, S101.5 and S51 are connected to the same column and row pins on the microcontroller, meaning that any software-defined keybinds will be shared by S101.5 and S51. I think this is a hardware issue, not a software issue.
If this was the intention when the board was designed, I apologize. But I think that 101.5 should be routed to column 2 or 3 to allow it to be used as a "space" and S51 to be a right bracket key.