They just confirmed on today's MSM Live that the bit in Poewk's part that sounds like Screemu creates vibrations that help que Screemu in to the song (y'know, since it's deaf).
It's such an unimportant detail, but I'm happy it's canon because it's a sweet little headcanon that I've had for a while.
BOOM more wubbox nonsense (drawn mostly from memory this time so forgive the inaccuracies LMAOOO)
this is Alva (center), the creator and “mother” of the Wublins. it’s very old and very tired, having been around since the time of the Celestials; in fact, it was one of Galvana’s first creations. supposedly it lived through the Cataclysm, but it refuses to talk about it. its body is pretty beat-up and worn looking since it often goes for long periods of time without replacing its mechanical parts.
also pictured are three of its “children”: Keeb the Screemu, Gnees the Poewk, and Vikath the Thwok. Keeb is a bit of a wild child, so Gnees often has to keep it in check in order to keep Alva from going insane. the two do tend to have communication problems, since Keeb is deaf but Gnees lacks the proper appendages needed for sign language, so it instead uses a form of morse code by blinking its eye lights. i honestly havent developed Vikath much but i imagine it’s a pretty quiet and well-behaved kid.