Red leaves in Laeliinae is never anything to be worried about. In fact, it actually means your light levels are just right.
Thank you for the info! The newest leave is less purple; we'll see if it flowers next year again. These thin-leaved rupics seem to be much easier to flower.
It is kind of getting too big: Largest Pseudobulb length=19cm, Largest leaf length=19.7cm, inflorescence length=83.8cm. Cattleya mirandae (plant) on Flickr