You didn't state the type of wire, but nevertheless I think you may have found some problems.
As I see it, the feeders from the transformer secondary to the main CB should have been derated to 80% for having 6 current carrying conductors in a raceway. Even if it is 90deg.C rated copper THHN or similar, that would be 430A/ conductor, x .8 = 344A per conductor, 688A per phase, protected by an 800A circuit breaker. Your conduit fill is OK, albeit marginal, for the conductors installed, but when you size them properly it will not fit, you will need to run another conduit.
The only caveat is that if those 2 motors are the entire load, then you can make a case that the transformer secondary is a dedicated motor circuit for a 336FLA load, in which case then the only problem is that the MCCB is too big. 336 x 1.25 = 420A, they should have used a 500A CB at the most, in which case the conductors are fine. Are you sure it isn't just an 800A frame with a 500A or even 450A trip setting?
The motor leads should have been at the very least based on 168 x 1.25 = 210A, so again assuming THHN, should have been 3/0. It appears as though they didn't apply Article 430.22 for upsizing the conductors to 125%; 1/0 THHN is rated for 170A. Although not required, I always recommend sizing the motor leads to the max. amp output rating of the VFD, just in case someday someone replaces the motor. So if the VFD is 150HP, probably rated 196A max output, 196 x 1.25 = 245A, I would have suggested using 4/0 THHN.