@quimkaos actually, you can find unicode.pf2 in usr/share/grub.
I copied the Antergos theme folder to usr/share/grub/themes & the Starfield folder to boot/grub/themes. I also copied all the fonts to boot/grub/fonts.
I did too many steps at once, so I’m not sure which one fixed it, but now I have the normal Antergos boot screen back.
After much searching, as I prefer Galculator myself, I figured out an easy solution.
Open pacman.conf & insert any package you wish to be ignored.
IgnorePkg = galculator
Simple, but effective.
I posted this here because this thread pops up when searching the problem.