Since nobody better qualified has chimed in...

The left hand bright switch has a pronounced effect, and the right hand one is more subtle- tho noticeable, to my ears, it's similar in effect to the bright switch on the amp itself.

If you think it sounds great without the bright switches on, don't switch it on-  I believe they are only there to compensate for treble loss with long cables between the amp, *lator and FX.

I'm not qualified to comment on your wiring, as I had mine pre-built by Nik.

FWIW, I use the left hand bright switch, but installed a treble bleed on the OD channel to trim off the highs, this gives me a nice sparkling clean but smoother OD.

Hope that helps.