Tilergal
TF
I agree, the lack of experience/training with these kind of tiles is showing up on the finer details, needs to be spot on when highlighting with a different coloured grout. Sounds like he realised he couldn't do the window properly and just finished the job and left hoping you wouldn't realise. What he should have done was remove the badly cut tiles and trim and got someone qualified in to finish off the tricky bits.It’s not as good as it should be.
Lack of attention to detail.
But bevelled metro tiles and tile trim, were never a match made in heaven anyway.
But your window could have been done to a higher finish.