Experience with pollination....

Interspecies crossings in orchids are exceedingly common within orchid genera in nature and it has been done in captivity since late nineteen century when the first hybrids were made in England. Even crosses between related genera are commonplace in the orchid family. However as the genetic relationship between particular species becomes more and more distant, hybrids become difficult to get. I would expect that an Epidendrum and a Restrepiella would not be compatible due to the fact that they belong to different groups within the orchid family that are not closely related. I have heard claims of Cattleya and Vanda hybrids, usually done by people with only a faint knowledge of orchids genetics, or maybe they were being facetious. I vaguely recall somebody registering a cross between between a Brassia and a Cattleya or Brassavola in the eighties that turned out to be an error. Sometimes due to the quirks of the orchids reproductive system, putting the pollen of an orchid into the stigma of another will trigger development even in the absence of fertilization. This has caused some spots of confusion over the years.

 

Apart from general curiosity if it would work, why would you want to make weird intergeneric hybrids?

 

In the beginnings of orchid hybridization, when people didn't know how to store pollen, crosses were made between whatever had flowers at the same time. This meant that there were many speculative crosses. Nowadays hybridizers prefer to use plants that already have a full suit of the choicest genetic traits rather than to start with scratch and produce plants that are inferior to things that we already have. However tastes in flowers are always changing, and new avenues in breeding are starting all the time, not all of which reflect the "dinner plate sized and very flat" aesthetics that is the ideal in the minds of many people.