Is this proper for a combination roof pitch? I know the tongue and grove bracing is wrong.
I don’t see a problem. What’s wrong with the additional bracing? Did you check the water staining for active roof leaks?
Areas tested dry, shouldn’t bracing be with 2x4 or is T&G fine, every rafter is braced.
Looks kinda ugly, and hard to evaluate the photo, but the T&G is fine, no structural ramifications.
2x material would be better than 1x T&G material bracing. Also, Bracing is best under / below rafter not to side of it w/ only shear strength of nails thru brace into rafters supporting it.