I will definitely try that. Thanks a lot for your trouble. There is not many resources online regarding btrfs and systemd-boot. It will help a lot of people.
In part, that is because systemd-boot doesn't really need much special config for btrfs. The only difference between systemd-boot with btrfs or systemd-boot with ext4 is you can specify the subvol to boot off of in the
options line of the entry.
For example, on one of my btrfs VMs it looks like this:
options root=UUID=99ddc98d-fec7-4184-9544-7aa6144eb369 rw rootflags=subvol=/@