The landlord might be able to push for an eviction; however, if this tenant pays their rent on time, there may be limited things the landlord can do regarding this matter. If this tenant has a month to month lease the landlord can decide to terminate this lease rather easily.

You and the other neighbors can do nothing more than what you have done. which is to notify the landlord of this situation. There is likely more strength in four different neighbors complaining rather than just you.

Gail