This may not be useful to you, depending on your particular situation, but I recently (last year) had to recover some shared secrets for VPNs that had been around for a very long time. I was able to do so because I still had (on my R77.30 management system,) some database revisions dating back prior to the advent of R67.
I extracted a policy revision made under R62 (its just a tarball). I obtained the R62 installation ISO from a checkpoint partner and installed it into a VMWare VM using "Other 2.4.x kernel Linux, 32 bit" as the OS specification. I then overwrote the R62 installation with the extracted tarball files from the R62 policy DB revision. Then started up via cpstart.
I was able to access the policy of the VM using R62 Dashboard and extract the ancient shared secrets which now safely reside in an encrypted password vault.
Obviously, the stars all aligned exactly to make this work for me, but who knows, maybe you still have an old backup or DB revision or migrate export from prior to R67?