Honestly, if someone can figure that one out and make it open source, you’re looking at the next frontier of modding for not just NHL94 but retro sports gaming overall. No reason it can be applied to all the classics of the past (TecmoSB, RBI, PES, etc).
It would need a robust algorithm to do the simulator part of the management sim.. Something like you see at https://www.whatifsports.com/nhl/ (pretty realistic yet random sim results)
The possibilities are endless. Setting up custom seasons/tournaments structures…. Even a scenario mode where you make a game 4-1 going into the 2nd/3rd period for more of a challenge. Pretty much anything.
MatchUP! was a just a proof of concept, but it went pretty far in a short time, and just one guy (pretty impressive)
https://pespatchs.com/2021/09/pes-2021-matchup-new-game-mode-option-file-editor.html