You ask a question - but this question has a context. Team I made an engineering decision without consulting A to H. They bamboozled the management higher up to accept this engineering decision. The result was that team I saved some time while creating a major problem for A to H. As a result, teams A to H are majorly pissed off with team I. Team I demonstrated that they are not team players, and other teams paid the price. You cannot expect no comeback.
As far as the wording is concerned, yes, you can use a dictionary. All three words are in the dictionary, with their meaning nicely explained. And at least two of them are quite common and should be known to someone knowing the word "pretentious".
But your problem is that team A-H suffered, and now it's payback time. Your team seems to be a mostly innocent bystander caught in the fire. You are not going to convince these teams to stop their behaviour. If they do stop, they will start something else.
I think your best move would be to convince the team leader of team I to publicly apologise and publicly admit that their actions were wrong, including informing management that their idea was bad for the company. Until that happens I expect there to be trouble.
If you go to HR, what I expect to happen is this: You say "please make them stop using complex language". They say "Team I's selfish behaviour cost the company lots of money and made us look bad". You say "but this complex language makes life hard for us. They say "Team I's selfish behaviour cost the company lots of money and made us look bad". Whatevery you say, they say "Team I's selfish behaviour cost the company lots of money and made us look bad". Eight against one. You have no chance.