I noticed tgp.slapsave.com is hosted by matchplay.events . I'm not sure if you run that website as well, and I'm also not sure if much has changed on IFPA's side of things, but it is running WPPR 5.2, I believe IFPA is onto WPPR 5.4 now.
I do run both websites, but it’s too time consuming to maintain. I’m happy to hand it over to IFPA but won’t be doing any updates in the foreseeable future. The differences between WPPR 5.2 and 5.4 as far as the calculator is concerned are very small though.