I think the language thing is just a fantasy trope.
The rahi (ussals in MNOG, gukko and ash bears in MoL, kikanalo in 2004 and Axonn's 2007 monstrosity) magically understand and even respond to Matoran language. Humans and dogs are capable of that, too, just don't ask a dog to lead an entomology lecture. Depending on how smart you want to call dogs, yeah, maybe visorak are smart. Other real world social animals also have politics, even plots to subvert, overthrow or kill weak leaders (wolves, lions, apes, insects I mentioned above). I'm a big fan of National Geographic and BBC documentaries, so I'm confident in that assertion. One I recently saw showed dozens of ant species cohabitating in the same nest, even communicating with each other, kinda like visorak.
Keetongu's species (another unnamed sentient species) had a society, language, and they used Tahtorak as steeds; all human-like traits we call signs of intelligence. Keetongu even fought Teridax one vs one in Time Trap, despite the makuta supposedly making the rahi, and were supposed to be on vastly different power tiers. I think Keetongu is rahi (not us) only in name, as he is comprable in power and intellect to many titans from 2005 until Infinity War.