What is the ruling on someone who woke up in Ramadan and found traces of seminal fluid, then was wounded and bled, then performed ghusl and completed his fast, being ignorant of the ruling?

The emission of semen during sleep (nocturnal emission) does not invalidate the fast. It is sufficient to perform ghusl (ritual bath) to cleanse oneself from janabah (state of ritual impurity). Similarly, the emission of blood from the body does not invalidate the fast. Therefore, your fast is valid, and there is nothing against you.