Some linguists with very good ears have learned vrusk language but cannot speak it (think Chewie and Han Solo talking). 

One linguist, Piegan of Fromeltar actually took on the challenge of making a version of vrusk that non vrusk could actually speak. Unfortunately, it mangles vrusk and looses a lot of the communicative band width the vrusk have with their antennae and body and hand movements being involved in communication. The vrusk tolerate it much like they tolerate the polyvox as a necessary evil. 

The Vrusk perspective is that the languages of the other core four lack the tonal beauty of spoken vrusk. Some non vrusk linguist totally rave over the beauty of vrusk poetry and 99% of everyone else thinks they're nuts. 

So anyway Piegan of Fromeltar developed piggen vrusk and a growing number of diplomats, business execs and what have you are learning it. 

In vrusk culture they don't have the concept of the human word bastard. The closest is orphan which goes back to ancient times referring to the young of another group that was wiped out. However, the vrusk have adopted the human term and with a vrsk approximation and applied it to piggen vrusk calling it bastard vrusk or simply bastard. ( they also refer to individuals that speak it as bastard speakers). The idea is that the vrusk consider it an illegitimate language, ugly, lacking beauty and nuance but are mildly humored at the other members of the core four for trying.