First of all I'm unsure that it's a valid way to create a save file by hex editing (or poking memory values), loading it and then resave it, but let's see:
List of the 12 byte difference:
0x13B AF - 73 = 60 (minutes?)
0x16D 18 - C3 = 171
0x16F 7E - 2C = 82
0x17B 00 - 01
0x17D 00 - B8
0x17F 01 - B8
0x18B 00 - 01
0x18D 00 - A8
0x18F 00 - 8B
0x19B 00 - 0E
0x1BF 00 - 0A
0x1BB 00 - 08
0x1DF 00 - 05
0x20B 00 - 01
0x297 00 - 20
0x29F 00 - 50
0x30F 00 - 50
0x357 00 - 01
0x37F 00 - 11
0x40F 00 - 03
At first glance I don't smell any checksums and I guess you actually played with the game, as those values changed from 00 to some higher number seems to indicate it.
You should try and first just change the bolded ones one by one, I think the game will only checks one of the address.
edit:
- There's also a debug mode, did you tried using it?
https://tcrf.net/Panzer_Dragoon_Saga
- Comparing with a GiriGiri save file found on google first result (different game but similar structure), 0x13B (unknown type), 0x17B (maybe number of hours), 0x17F (unknown type) seems to be more likely the one you want to change.