Miles,
The QoS values for your app server are very low (e.g., under 0.95) which is indicative of a system that is either in need of further tuning or possibly at the maximum load it can support. For example, a SPECjAppServer QoS score of .96 means that 4% of the transactions are NOT meeting the required response time criteria (i.e., the transactions are taking too long - for whatever reason). A QoS that is failing (typically under ~95% for the three QoS constrained workloads) is an indication that you should be either *decreasing* (not increasing) the Tile count, or tuning the OS/Hypervisor and/or guest software stack to address the excessive transaction response times for the affected workload(s).
*Note, the guidance that we can provide on this forum is limited to assistance related to initial harness, guest VM, and the example guest software implementation. From your posts, it seems you have successfully run multiple Tiles on your testbed. Scale-up performance tuning assistance is beyond the scope of our support capacity. Tuning such environments depend heavily on your particular hardware/software infrastructure and associated configuration.
I would recommend closely reviewing the details of the hardware and software tuning for published SPECvirt_sc2013 results and compare with your existing hardware and software setup. Assuming you are using a similar hardware and software configuration, there should be enough information in the FDR and data collection .tgz to provide further tuning information.