the cockroach problem: if there is no active infestation, likely not BUT you need to read the sellers disclosure form very thoroughly. If there is something on there that could be construed as applying to the roach situation, do not be dishonest at all. It can come back to bite you, really hard.

The noisy neighbors; while nobody can reasonable expect no noise, if this is beyond what one would consider "normal" or "typical", you should disclose it. Again, it is a material issue that could be used against you if you are deceptive in any way.

possible consequences?

well, with the roach problem, if there is an active infestation, you would very likely be required to pay for extermination. The buyer could seek to rescind the sale if they would have not taken the unit knowing of the problem. If they win would be up to the judge.

Since the noisy neighbors can't be "cured", most likely a buyer would seek a rescission of the contract. How a court would rule would be a gamble.

You should be discussing this with your RE agent.