In case you are not familiar with that accent, think of what an American news anchor or actor sounds like when he's on screen. It's considered a "plain" or "vanilla" accent compared to other United States accents.

This would likely make Cortex feel upset, because he might feel his real voice lacks any sort of identity. I can easily picture N. Tropy mocking him for using a fake accent... until someone points out that Tropy's accent is ALSO fake.

Tropy is definitely British, but he's not an upper-class Brit like he pretends to be. He has a cockney accent that he unleashes when he's taken off-guard or especially pissed off. Tropy has humbler roots than he lets on, and he's not proud of it. That's why he hides his real accent.

And Cortex just laughs at him, even doing a perfect impression of Tropy's real voice to get laughs from N. Brio and N. Gin. As it turns out, Cortex isn't just good at faking accents... he's also damn good at doing impressions.

So... my headcanon is that Cortex's parents are descendants of immigrants. Cortex's dad - name unknown - speaks fluent Spanish, while Cortex's mom, Sharon, speaks fluent Romani. Both of them learned English growing up while performing on the vaudeville circuit with their respective families. (Remember, this was a very long time ago, Cortex is an old man.)

Cortex's dad was largely detached from his son emotionally, as he was disappointed in his son's nerdy pursuits of science, feeling he would never amount to anything. He did, however, at least bother to teach Neo how to speak Spanish just as fluently as him. Cortex takes great pride in his pronunciation skills.

However, Sharon not only did NOT teach her son a word of Romani, she went out of her way to make sure he would never understand a word of it, just so she could freely talk shit about him, insult him, or hide secrets from him just by speaking Romani. When Cortex finally purchased a book on the Romani language decades later and finally learned all the nasty things his mother called him, he nearly had a nervous breakdown.

And do you know who else talked shit about him in Romani? Cortex's grandmother, Sharon's mother. Oh sure, the old lady pretended to care about Cortex, but she believed every lie Sharon told her about him. How useless and stupid he was... how ugly he was... how much of a burden he was... how much of a loser he was for reading all the time... and making silly inventions...