What is the legal ruling on using partners' funds, designated for importing clothes, to establish a factory without their knowledge, and is it permissible to fix the value of these funds in US dollars when repaying them, taking into account the depreciation of the local currency and the delay in payment?

What you did by taking people's money and investing it in the factory without their knowledge is a mistake and an transgression that obligates you to guarantee the money in all circumstances. It should be returned at its purchasing value at the time of the transgression, whether in gold or dollars. The principle is that the money should be repaid as it was taken. It is not permissible to agree to repay it in another currency except at its value on the day of repayment. If the currency's value decreases, the deficit must be compensated with a currency different from the original denomination to avoid usury. It is not permissible to delay repayment except with the consent of the rightful owners. Repayment is obligatory, even by selling the factory or other assets if they do not consent.