Welcome Mollycart1
I can't answer your question about the flower on your vanda, but I can encourage you on growing vandas under lights.
I have been told that I can grow vandas under lights but they will never flower. NOT TRUE. These pictures are here to encourage you.
I grow mine under a 600 W HPS light. It is on a light mover so it isn't constantly under the full light. I spray the roots every morning, with fretilizer in my water. I have a humidifier in that room but spraying the plants every morning also helps keep the humidity up.
Here is a pic of my set-up in my basement, and two of the plants which I have brought into bloom for the second time. Sorry about the color on one edge of the pic. With the light moving across the bench, it is almost imposible to take a pic without the color of the light catching one end.
NOTE: The white shower curtain is there only to prevent me from spraying water on my wall.
and let us know how it works for you. - - Marilyn