The ticket mentions Boot Repair, which is the first thing that comes to
mind: https://help.ubuntu.com/community/Boot-Repair
Boot repair is obviously tricky because you have to have something bootable to initiate the repair. Practically speaking, I think the best option is to better support dual-drive installations. It should be possible to maintain two EFI partitions in a, b style when the user selects to have a mirrored-disk configuration. In fact I've been doing this on my Fedora Linux systems and I've even written some scripts to support it here:
https://github.com/gregory-lee-bartholomew/bootsync
Disclaimer though -- I use systemd boot and zfs, not the default grub and btrfs that most Fedora Linux systems are configured with.