Just as an aside, Glen writes "There is a typo in OPL-update though, so it does not run update-OPL-statistics.pl (it is missing the .pl in the filename), but it does run load-OPL-global-statistics.pl." This explains why in the installation instructions I had to add a section https://webwork.maa.org/wiki/Installation_Manual_for_2.15_on_Ubuntu_20.04_Server#Initialize_the_OPL_local_statistics_database_table to run the command update-OPL-statistics.pl separately. I never tried to trace down what had changed to cause that to be necessary. I'll have to try to remember that I should remove that for 2.16.
Also OPL statistics are no longer being collected as far as I know. It would be a good idea to setup a server to hold the data and start collecting that data again. The current data is pretty old.