Thanks for checking the game out!
I just did some bug fixing and managed to solve the issue with the archaelogy/research sites. However, I was incapable of replicating the bug with the grinder (the blender thing) or the bug with the guests/visitors not arriving anymore. I did make some changes that will hopefully stop the problem with the guests from happening again, yet I can't be 100% sure (so for anyone reading this comment, feel free to inform me if you encounter this bug).