Personnaly I'm pretty sure that no one will care about canon ending as long as you don't choose a canon romance
I think that all you need to please the fans is to acknowledge their romance choice (even for one scene only),
For exemple you can do something like TOS2, where you learn that the hero of the first game travel with his closest "friend" at the end of the 1st game(the 1st has different scene at the end in fonction of who is the closest to the hero), the hero of the first game(Lloyd) ask the hero of 2nd game(Emil) who does he thinks he travel with, no matter who you answer Lloyd will say that Emil guess right and later you have one scene between Lloyd and the character that was chosen.
It's not a lot but it's enough to please.
You can make a game with a SOTW LI has a side character who help for a few scene, the MC see from afar the LI with someone describe has a snow elf, later the LI say that he/she is waiting for someone then the MC can ask if he/she's waiting for :
"the snow elf boy with you the other day" or "the snow elf girl with you the other day".
the LI will yes no matter the choice will they that the elf is someone dear to him/her and you can ask if he/she mean that they lovers, if you ask the LI will they yes if you choose the correct twin earlier , in the others case the LI will say that the twin is just a dear friend.
People who played SOTW will understand and choose what they want and for the people who didn't will not really care about it, and that is just 4 different variation of a single scene so it not "a lot" of work.