I could imagine developing some sort of "LearnedFactor" function that takes as input the firing angle along with the enemy's position, velocity, maybe more complex features like precise MAE, etc. As long as the function is invertible with respect to the firing angle you could then do KNN with those instead of GuessFactors.
The biggest challenge will be how to deal with different settings in recorded and aiming. Guess Factor indeed do this with orbital movement assumption, and PIF with not moving out of wall.
I'm thinking about some end2end deep model, where transformations between recorded and aiming angles can be learnt automatically. E.g. Given a sequence of historical wave intersect location, movement and bullet hits, try to predict the next wave intersect location.