Hm, that's odd.
Currently the librewolf-bin.desktop file is indeed not used, I'll probably remove it in the next version.
At the moment this package just uses a prebuilt binary built with the librewolf PKGBUILD, which already includes the librewolf.desktop file in the proper place.
At some later point this package might switch to using an 'upstream' binary, which is when it might be needed again.
But more the the point, or rather to your problem: Even though the '-bin' desktop file is not used, the regular one is, and at least on my system can be found in /usr/share/applications/librewolf.desktop (and LibreWolf appears in the (xfce-)menu). Could you check if it's there on your system as well?
It should be; on my system pacman -Qo /usr/share/applications/librewolf.desktop shows it as being installed by this package (/usr/share/applications/librewolf.desktop is owned by librewolf-bin 67.0.2-4).
Pinned Comments
lsf commented on 2021-11-10 12:14 (UTC) (edited on 2023-04-17 07:18 (UTC) by lsf)
https://wiki.archlinux.org/title/Arch_User_Repository#Acquire_a_PGP_public_key_if_needed
gpg --keyserver hkp://keyserver.ubuntu.com --search-keys 031F7104E932F7BD7416E7F6D2845E1305D6E801/edit: starting with 112.0-1, the binaries are signed with the maintainers shared key, so
gpg --keyserver hkp://keyserver.ubuntu.com --search-keys 662E3CDD6FE329002D0CA5BB40339DD82B12EF16should do the trick instead. I've also signed the key with the previously used key, so you have at least some guarantee that it's not a malicious attack :)