This is a clever little word game, once I figured out what was going on it was pretty fun! I don't really have any expertise in word games so I'll only go into detail on this one thought:
The only thing that came to mind was that the score doesn't feel like much of a motivation because It's just too much of a black box to know what a "good" score really is. I think a frame of reference to compare your score to would go a long way to making the accomplishment felt. Something like an algorithm that calculates the theoretical max score based on the given letters. The alternative would be to make the levels more puzzle-y handcrafted levels that give the player clear objective markers of success. Either way, a score alone isn't enough to reward the player, they also need a context to frame it in.
That's all I have for feedback, this was a lovely little word game and I wish you all the best in the jam! Keep making games and have fun!