Is it sufficient to give a warning against cheating in answers to earn money from a survey website, or is it obligatory to compel those who register through referral to also warn those who register through them? And are the points specified by the website (200 points) for completing five surveys considered an unknown percentage?

Dealing with websites that offer earnings from surveys, advertisements, and the like is not free from Shariah-related concerns. Earning through referrals (يحال) involves an element of jahalah (uncertainty), as it depends on the work of the member, who may or may not perform it, and may or may not reach the required number, thus rendering the deserved points unknown. As for the possibility of fraud by individuals you refer to the site when answering surveys, this is not a significant factor, as it is merely a possibility, especially if they have been warned and cautioned against cheating.