For issues like this, please make a ticket in our discord https://discord.com/channels/940907977014120488/966592678768807946 . Someone has already reported this so it'll be looked into when someone has the time.
Went in game with Yin. Saw hand was there. Respawned fire giant using it. Giant died, hand stayed. Then spawned giant again, then hand disappeared. So seems like modpack issue with the fire giant summoner block. :(
Claim chunks do not add up together. That is just how the FTB developer decided to do it sadly. So yes, it is meant to be like that and the workaround is being allies of each other to "share" chunks which is what you're doing.