Can paralyzed diaphragm symptoms get worse/how much?

The diaphragm provides the majority of operative control, mostly passive, involved in breathing/air exchange. Without it the chest wall muscles must take over all of the work. What this means to an individual patient and how their case is managed must be determined by the doc treating each individual case. It is not a good thing to have this.

Yes, depending on cause and comorbid conditions, such as pneumonia or pleural effusions among the most common, symptoms may worsen significantly. Seeking medical attention timely is critical.