My wild speculation is that someone saw the "Loading ROM Image" message and decided they didn't want to so openly reveal that the disk contains a copy of the Model 4 ROM.
I haven't looked at the files you guys have attached, but are you sure its not the loading from serial port message that changed? I've always seen Loading ROM image when its loading Model_/III from a floppy. What I've seen the most different is the messages saying the floppy drive isn't available in English, French, German, on Non GA and GA machines.