Lost an LTFS Volume. looking for possibilities to recover data.

[HKPune]

I am using an Hpe LTO 6250 drive connected to mac os 10.11.6 using HPE LTFS 3.4.2.

I have archived an tape about an year ago and kept in shelf. Recently tried to mount the tape to restore some data from it using a different HPE 6250 drive and HPE LTFS 3.2.0 it said "mounting is failed; index xml pcdata parser is failed". Then I went to know that this tape is written using HPE LTFS 3.4.2, So I reinstalled the version and tried but the result is same.

1st error image 

Then I tried "ltfsck --full-recovery" it took some time and by the time it completes it showed me that the tape is consistent. Then it mounted what I found is 50% of the data is there and the rest restored to lostandfound folder in 512kb blocks in a inaccessible format. So I tried to get the rollback points and it shows the current point as 43rd generation and the the same eror "index xml pcdata parser failed; can not find roll back points". It is even failed when I gave the command "ltfsck -g 42 -k 0 " with the same error. I don't have a 2nd backup for this file. Can anyone help me with this?

full recovery and rollback info