For purposes of a test, you can ignore the directions. Try any and all of the 4 logical ways they can be arranged.
1. mylar to listener, tweeters out (per directions)
2. Swap 'em L/R for mylar to listener, tweeters IN.
3. Rotate in place: results in mylar away, tweeters out
4. Swap em back L/R for tweeters IN and mylar away from listener.
#1 is Magnepan preferred.
#4 is the way I have my panels.
I'll go with whatever YOU prefer, in your system! It's too easy NOT to try, don't you think?
My original MG-1s were mylar away. I am told that sometime in the '90s, Magnepan decided to face the mylar TO the listener.
This will be the cheapest tweak you EVER try. Even removing the fuse will cost a few grams of solder and the electricity to heat up your soldering iron.
OH, each swap will require a little effort to optimize. When I did the rotate, they fell so naturally into place I have yet to mess with them again. But, I've been setting up panels for a long time and can get 'em pretty close to perfect in pretty good time. Perfect setup? takes longer.