From archlinux32 install:
... :: Replace pacman-contrib with core/pacman? [Y/n] warning: cannot replace pacman-contrib by pacman ...
and the next keyring shitstorm approaching
error: jfsutils: signature from "Tyler Dence (Build Key) <email@example.com>" is marginal trust :: File /var/cache/pacman/pkg/jfsutils-1.1.15-5.0-i686.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)). Do you want to delete it? [Y/n]
sudo pacman-key --refresh-keys resolved the issue, then an update of archlinux32-keyring followed with pacman -Syu. I guess you need to sync/update archlinux32-keyring-20180603-1.0 first.
PS: Looks like a new maintainer joined archlinux32
gpg: key 443904EC9EC51A8A: "Roelf Wichertjes (archlinux32 master key) ...