Hi, I'm the developer of a protection plugin for Sponge. Some users were reporting me that when using RLCraft the pvp protection was not working, so I did some search.
I setup a dummy plugin that logs any event that were fired by Sponge and.... turns out that when the mod is active the damage events are not fired! Infact I removed your mod from the RLCraft modpack and suddendly the pvp flag from my plugin worked as intended. Also the dummy plugin logged attack and damage events as well, leading to conclusion that there is something wrong going on between your mod and Sponge, which is really strange. If you wish you can DM me on Discord (JimiIT92#5322) to see exactly what is going on or if you want some help in troubleshooting this issue