I am not sure if your name for this is correct. I can see lot of variation on the flower with that name.
Ofcourse it has Oncidium in it but may also have Miltonia!!
Yes your curiosity of the name is correct because the two genera involved for Oncostele are Oncidium and Rhynchostele.
On the other hand Odontocidium: Odontoglossum and Oncidium
Colmanara: Miltonia, Odontoglossum and Oncidium (Now where 'R' came into the hybrid name, I have no idea). I dont know if there is a compulsion of naming hybrid by combining the name of the parents, its just a trend.