I grow a Wilsonara but not the one you have, so far I find it like any other Oncidium, really likes being kept moist, water hungry here in our area. I just use typical bark mix, smaller type, not the very chunky ones. It actually taught me just how much of a water hog it can be. During the long hot and dry months, I water it freely everyday here. My orchids are positioned in my growcamp so they get more air around and easier to water them. But as seasons change, slowly scaling it down and I bring it indoors during winter. But it still gets watered, but with intervals now, about once a week. It actually blooms here during the cooler months, since the hot and dry temps here is just excessive. Seems to be happiest at 85F max and low temps at 45F to 50F.
During late Fall to winter, it is by our south facing window upstairs. Actually I have even let this plant sit in water for a couple of days, but it was done in Spring to early Summer, and the dehydrated pseudobulbs actually plumped back, though there is still the sign of wrinkling, but it recovered. That is how I found out just how much moisture Oncidiums needed.
On the very hot days outdoors, it is protected by the shade from the canopy of city trees here. Outdoor temps of 100F and more it survived very well provided it gets watered thoroughly early in the day and lots of air around. It is not like a vandaceous orchid or dendrobium which can tolerate much higher light levels, and will prefer more light than one provided for a Phalaenopsis. That is what I have seen with my Wilsonara Hilda Plumtree 'Purple Wings' Everything will be rather subjective too, just depends on your ambient growing conditions there..you may have better humidity levels than we do here.
This is mine in bloom last Jan 2016 indoors: