I did take a look at the switch save and xv2savdec.exe.
PC save filesize is hardcoded into the exe as 0xB08C0 & 0xB0818 byte, switch version is 0xB0800 & 0xB0780
PC save has an extra 32 byte MD5 header, this header is not present in the switch version.
After reversing how the tool works, i could successfully write a decrypter for the switch version.
here tool + source:
https://www.dropbox.com/s/j1zznqhkmmbiax0/xv2savdec_switch.zip?dl=0
place "xv2savdec.exe" in the same folder as "savefile1.sav" and run it to create "savefile1.sav.dec"
Note1: I only reversed the decrypt function, not the encrypt
Note2: XV2 Save Editor 0.7.4 does not fully work with the decrypted save, a new editor needs to be made.
Note3: i'm not even playing the game, so don't expect me to finish this, it was just a quick 10 minute work to make this proof of concept tool.