Is a partner who owns 70% of the capital entitled to demand that his partner, who owns 30% of the profits (solely for his effort), bear 30% of the project's capital loss after it has incurred losses for a full year without income?

The contract concluded between you is considered a corrupt Mudarabah (definition) (partnership) because the share of the Mudarib (investing partner) is both an undivided portion of the profit and a fixed sum at the same time, and this invalidates the contract.

Therefore, you are not entitled to any share of the profit; rather, you are entitled to a fair wage (Ajrat al-Mithl). Similarly, your partner is not entitled to claim compensation for losses from you; instead, you have the right to demand a fair wage from him.