If the other engine from which you these assets come differs not only in which axis is up (Y or Z) but also has flipped axes (i.e, left-handed vs. right-handed coordinate system) then that also messes with your rotations.
Blender: X points right, Y points forward, Z points up
Unreal: X points forward, Y points left, Z points up
Unity: X points left, Y points up, Z points backward
Godot: X points right, Y points up, Z points backward
CryEngine: X points right, Y points forward, Z points up
When moving assets from one engine to another, you’ll often have to also rotate objects by 90 degrees on Unreal’s Z axis, or, if one axis is flipped, invert the sign of the rotation (+30 degrees become -30 degrees).
From the screenshot it already looks like you’ve narrowed it down to Z-axis rotations, I’d try negating the Z rotation first. It could also be that the two scenery pieces don’t match up because X and Y must trade places and Z needs a +/-90 degree rotation.