As of now construction work is still ongoing but the Bundesliga club would prefer to wait with further phases until the COVID-19 situation becomes more stable. To do this, approval from DFL is needed.
As you may remember, SC Paderborn 07 began reconfiguration of their stadium earlier this year. The goal is to meet basic infrastructural requirements of the Bundesliga, that is 8,000 individual seats (currently 5,800 out of 15,000 total capacity).
The project has been divided into two separate phases. In February the first one began, seeing another floor added to Benteler-Arena's western club building, along with a strip of new VIP places on top of the current stand. These works are not impacted by the COVID-19 crisis.
However, according to the most recent statement of the club, there's desire to postpone further works until the situation is more stable. As of today, Germany is the 5th globally in terms of number of identified COVID-19 cases (34,000+ and climbing) and non-essential works should be postponed.
The club will not decide to put its project on hold independently, however. Because it's a league requirement, Paderborn are in talks with the DFL (Bundesliga governing body). Should their conditional license to play without 8,000 individual seats be extended, they will wait with further works.
The second phase would include addition of an overhanging second tier atop three remaining stands (north, east and south). This way the seated capacity would exceed 8,000, while total crowd size for games would be 18,000, as seen in the below rendering: