They aren’t suggesting using a grease pencil as a better alternative to a graphite pencil, they are saying that the Russian cosmonauts used grease pencils before moving to a pressurized pen.

You don’t need to say “no thanks” to it, no one is suggesting using it. The first comment was ambiguous, but your response to this one is just baffling.

“here are some ways you can verify to those doubting you, with proof, that this is a real issue you’re going through”

“I can’t do those things and yikes”

Did you make this post just to complain, or are you looking for a solution? And the apartment might be under your parent’s name, but what’s stopping you from talking to management yourself? People are legitimately trying to help you, but everything you say makes it harder and harder for people to take you seriously.

I 100% would not pair my phone to a public toilet just to flush it

Invest in a cheap audio recorder and leave it running when you notice them acting up. Or, if they do it in response to you making noise, intentionally make some (mundane, reasonable) noise and catch the response.

If the landlord wouldn’t believe it when you tell them the tenants are acting obnoxiously, then there’s no way to phrase that differently to make them take it seriously without giving them some evidence of it.