I can associate with that !
Sometimes you have to use a loco cab view in -freeintcam ... and see the placement of the asset (too high, too low, falling off a platform ...  etc ...) and move the building itself, and then move the assets into fine tuned placement.
Or you can add the tag: height range -50,50 to the building config file, raise it up, and drag the small assets around.
Sometimes you have to zoom in, or zoom out, or get way down at a low viewing angle, in order to grab the assets inside the terminal.
There is a "Trig" that is a surveyors tripod, that is great for marking 4 corner spots, for repositioning the building exactly where it was previously