Is it permissible for an investor to agree with capital owners on a 50% share of the profits, knowing that the project owner takes 40% of the profits for management and the investor takes 10%?

If the owners of the funds give their money to you for Mudarabah (profit-sharing), you are not permitted to give it to another person to engage in Mudarabah with it, except with explicit or implicit permission. If you are an intermediary or a broker between them and the one who manages the funds, they must be informed of what is taken from them as brokerage fees; otherwise, that would be consuming their wealth unjustly.