I tore out the carpet and pad from one of the larger rooms in our house, and saw that the subfloor is raised up 3/4" to where it goes under 2 different load bearing walls. the rest of the floor is level, and these two peaks are fairly isolated, but i figure to carve away the peak, i'll end up going through the subfloor completely. i've been installing the engineered hardwood throughout my house without issue so far, but this seems like a good time to call a contractor, who can assess the substructure in the crawlspace under the floor. thoughts? advice?

Sometimes a load bearing wall will have a beam directly under it to transmit the load to the foundation. The beam may be a glu-lam that was made with kiln dried wood. The original floor joists were only dried to about 19% moisture content. When the joists dry completely depending on humidity in the air they will sometimes shrink a quarter of an inch. If the joists were sitting on hangers this would account for some of the difference in height. This difference in sub-floor height is also apparent at the top of a hardwood stairway that was kiln dried and installed when the framing was fresh, and later the floor joists dried out while the hardwood stairs would not shrink, leaving a high spot where the steps join the flooring. I would guess that the framing was a major part of the problem.

thanks for the info!
i have a contractor coming out today to see what they can do about it.