Your Alum spacers look neat, can't quite make out in pic, are they wedge shape? However if they are longer then your steel axle welded perches, I would suspect that the flanges will eventually begin to crack, and can't see why that would cause any structural harm, nor what they are needed for to begin with, since u bolts keep them aligned? i guess you could say this a backhanded compliment.
I see you did mention they are for pointing pinion down.