There is no way to replace brain areas of damaged but time and speech therapy usually helps considerably.
Seizures starting in a localized abnormal area can be helped by removing that area surgically. "Generalized" seizures that start all over cannot be helped by surgical removal of brain areas but there are options for disconnection of stimulation of either brain areas of the vagus nerve in the neck by implanted pacemakers.
In summary, most seizures are not treated by surgery because medications work. When medications are not working optimally, surgery can be a consideration in some if the extensive work-up leads to reasonable surgical options.... so only a minority for surgery overall.
Most surgeons use little titanium plates and screws for skull repair which confers some immediate stability. The bone usually grows together over 6 months or so with some variability.
Is your meningioma really 5x5x3mm not cm?
I don't think anyone in their right mind would suggest treating that if it is mm.
Overall options include observation with serial MRIs (always a choice but really the only reasonable one if that is in mm), surgery or radiosurgery. Radiosurgery is computer-guided radiation, usually in one session (sometimes 3-5) which is proven to work usually more by stopping growth with slight shrinkage, not disappearance. All these options should ber discussed in anyone with a meningioma. If it is tiny as described, observation is the only reasonable option. I usually use 3D MRI sequences for observation so that small changes in volume can be seen by computer matching way before radiologists see a change.... this with a view to discussing treatment as opposed to further observation. Again if tiny, even a small change should not prompt intervention.
Meningiomas cause symptoms isf they get large and affect adjacent brain or sometimes if irritation of adjacent brain lowers the threshhold for seizures. Otherwise no particular health risks.