I seem to be able to import larger filesystems just fine
$ juju import-filesystem ebs vol-0adf6e5d88f10e999 data
importing "vol-0adf6e5d88f10e999" from storage pool "ebs" as storage "data"
imported storage data/5
$ juju storage
[Storage]
Unit Id Type Pool Provider id Size Status Message
data/5 filesystem ebs vol-0adf6e5d88f10e999 4.9TiB detached
I seem to be able to import larger filesystems just fine
$ juju import-filesystem ebs vol-0adf6e5d88f 10e999 data f10e999" from storage pool "ebs" as storage "data"
importing "vol-0adf6e5d88
imported storage data/5
$ juju storage 10e999 4.9TiB detached
[Storage]
Unit Id Type Pool Provider id Size Status Message
data/5 filesystem ebs vol-0adf6e5d88f