Tweeters got me baffled.

Not that important. The reason for he offset is to minimize baffle edge diffraction..if you place a tweeter equidistant from the sides then you increase the amount of baffle edge effect at specific frequencies - the worst case would be a circular baffle with the tweeter at the center.

If they are mirror imaged,try switching the left and right to see what happens in your listening room.

I forgot to mention,I've seen them both ways.Some tweeters in,others tweeters out.It must depend on overall design,plus maybe what the makers think will work best.But they still don't know everybody's situation.

When you try switching the speakers side to side to see which you prefer (if either at all) listen for 2 things. 1) Clarity from reducing side wall reflections a tad (when tweeter is on the outside) and, 2)Soundstaging which should be slightly wider when the tweeter is on the outside and more focused when on the inside.

The key words are 'slightly' and a 'tad'. Many, if not most, folks wouldn't detect the difference for a lot of good reasons.

It only makes a difference if you hear it.