If this is visitors car spaces then your visitors have the right to park there when visiting. However, if these are visitors only car spaces, then you (nor any other resident) has the right to park there overnight!
Alternatively, some complexes I know of have residents only parking on the premises. Then no visitors parking is allowed.
You previously posted regarding parking on common property, that being the driveway out the front of your unit. Visitors parking is also common property. Residents parking that is not numbered would I assume be a first in best dressed basis. Then parking “outside” may be the only option.