You won't find your answer in the lease. Lease terms are likely irrelevant to mold issues, no matter what the lease says. AForget the lease.
You may consider contacting the local government Building Code Enforsement. They may come and look at the mold and identify if it is a dangerous type. Even if his has been "removed" it can be tested. The spores are very small, and can float around in the air. They will be on walls and floors the look clean, and even that have been "cleaned." Also, it may be in other apartments, and behind wall that were not removed.
Some mold is not a big deal. But some mold is very dangerous, especially if you have children. Black mold is generally not good. Trying to clean it only makes it worse. Moving it, or cutting into it makes it worse. It must be professional removed.
I would not touch it. I would not smell it. I would not touch anything that touched it. You might need to get out of the appartment. This is more likely true if you or persons in the apartment have been sick, tired, or coughing. Please note I am not a doctor.
Other tenants may be in a similar position. You may ask them.
In bad mold cases, in addition to becoming ill now or later, one can lose all clothing and furniture because the mold spores get into these items, and they cannot be cleaned or disinfected. And they grow.
If the mold is a bad type, you need a lawyer that does mold cases specifically, ASAP, to get good personal advice, and help moving if it is needed. Don't worry about the cost now, they should talk to you for free. A lawyer should help you get the mold tested too.
You may have the mold tested your self, for a fee.
You may want to see a doctor if you have felt ill.