What is the ruling on trading in foreign currencies (Forex) using the speculation system, where the profit ratio is 60% for clients and 40% for the speculator, with an Islamic account that avoids usurious transactions, and trading is halted when losses reach 20% of the capital, and without trading in gold and silver?

What you mentioned suggests that you take the money for speculative trading in currencies in exchange for a percentage of the profit. There is no harm in this if the Sharia-compliant controls for currency exchange are observed, including instantaneous possession (taqabud) at the time of the contract. This is based on the Prophet's (peace and blessings be upon him) saying: "Gold for gold, silver for silver... like for like, equal for equal, hand to hand. If these types differ, then sell as you wish, if it is hand to hand." This ruling applies to currencies. It is also possible that you are guaranteeing the principal capital, and this is impermissible.