Does a failed separate ZIL disk mean the entire zpool is lost?

A server I look after had a 65TB ZFS RAIDz1 pool with 8 x 8TB hard disks 
plus one hot spare and separate ZFS intent log (ZIL) and L2ARC cache disks 
that used a pair of 256GB SSDs. This ran really well for 6 years until 2 
weeks ago, when the main cooling system in the data centre where it was 
installed failed and the backup cooling system failed to start up.

The upshot was the ZIL SSD went short-circuit across its power connector, 
shorting out the server's PSUs and shutting down the server. After 
replacing the failed SSD and verifying all the spinning hard disks and the 
cache SSD are undamaged, attempts to import the pool fail with the 
following message:

NAME       SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
clustor2      -      -      -        -         -      -      -      -  UNAVAIL  -

Does this mean the pool's contents are now lost and unrecoverable?

Andy