How does engine geometry affect flight stability?
The problem appears to be mostly the effect of a larger cowling, moved more forward, that generates significant lift when operating at higher AOA and has an effect similar to moving the entire wing forward, or moving the center of gravity aft, partially unloading the horizontal tail in the flaps up low speed regime and making the pitch stability a bit neutralish.

Seaplanes suffer from a bit of a similar effect in yaw from adding floats. The floats add quite a lot of side area forward which reduces the fin's weathervaning tendency.  This is why you usually see additional fins added to the tails of float planes to restore the original yaw stability.

In the case of the MAX it appears the pitch destabilizing effect of moving the cowls forward really caught them by surprise because the problems were only found during flight test.  To restore the original relationship of the effective center of lift to CG would have required some pretty radical redesign, say like adding a plug to the forward fuse to move the operating CG forward, which would also require making the tail bigger... and off we go on the one-thing-effects-another design change merry-go-round without end.  What a mess.  They were really between a rock and a hard place, and an artificial stability system using the stab trim system to work around what was a fairly narrowly focused problem provided a relatively easy escape route.