Problem modding Inversion savegame, help needed!

Hey folks,

i'm trying to mod my Inversion savegame to get the multiplayer trophies done. I verified that the info is stored in the save. I even found the locations of online XP, challenge status etc..

Problem is when i say modify my XP from 20k to 50k, then Inversion tells me my save data seems corrupted.

Here is how i do it:
1. Copy Save -> USB -> PC
2. BSD -> decrypt PFD (SAVES.CFG) <- this is the actual "save"
3. edit my stuff in HxD
4. BSD -> update PFD (full)
5. BSD -> encrypt PFD
6. copy back to PS3 (save seems legit during copy process, only inversion game itself says it's broken)

Another thing i see is that a very large portion of the save (once decrypted) is still crypted. This large (almost 1MB) data block changes everytime something happens to the save, like playing a match or so.
I think that inside this block are some verification patterns, but i have no idea how to actually edit those.

Here i am, needing help to figure this next step out. (if it's even possible)

thanks in advance!