some good news, I found out how to limit teams showing up on the "EA Hockey Night" animation and the "Other Scores" screen, one issue is you can't go below 18 teams or it will crash.
the first example I took my NHL 78 rom and went to location 00018032 and changed 701A to 7012, now only those 18 teams will be shown, no N/A
the second example I took NHL20 and changed 701A to 7020, now all teams will be shown.