Get rid of that black lines !!!

[TIG]

I made it symmetrical about the Y axis [green] plane so the two halves ARE matching and 'consistent': based on the right-side which I sliced off and copied/mirrored.
It may be that you didn't model the right-half exactly axially, so the parts are askew.
Certainly the two sides has slight variations, but so slight it looked like sloppy modeling and not a minor variant on one side only...
Since no one but you can know what you think it ought to look like, then I suggest you adjust the SKP I have given you to suit your desires.
You can easily rotate its geometry so that the right side is say axial on the red X plane, or any way you want it to be.
Then draw a large temporary face as a vertical plane on the Y axis [green] and intersect to make the cut line and erase the geometry from unwanted skewed half and the temporary plane/cutter.
Then make a copy of the 'good' half [Move+Ctrl], set well off to the left side, and use Scale -1 on it to mirror it as the new left hand part.
Snap the left part onto the right part.
Now you have a solid object, that's reconfigured so its two symmetrical sides are arranged as YOU wish...
You have spent more time discussing this that it would have taken to re-model it from scratch, entirely within SketchUp...