I realized something regarding the large B and large F in the first position of serial numbers. I recognize this font style used on the serial numbers of American currency back in the day (the U.S. may still use it today), and I am thinking the big B and big F may have been just a stopgap measure until the Bank of Canada got a new die created for the smaller B and eventually smaller F on a regular basis. The small B for the first position was definitely in place by late 1989, and the small F was used in the first position on a regular basis by late 1994 or early 1995.
No large G was used for printer letter G on the $5 notes, possibly because the decision on the $2 bill's demise was finalized and enshrined into law by late 1994, and the final supply of twos were printed by late 1994, but its demise was not announced until the Federal Budget in late February 1995 (the $2 bill used denominational letter G, so the ceasing of printing $2 bills in 1994 meant one less denominational letter at that point, so there was no need to create a new die for G like they likely did with B and F). And there was no large H for the $5 notes in the early 2000s because of the looming serial number font change for all five of the current banknotes and the phasing out of the letter/number dies that was in use from 1969 through 2004.