You updated PKHeX, but not the plugin... and are receiving errors on the plugin, which isn't up to date.
Might be a good idea to update the plugin instead of assuming it works regardless of PKHeX version?
You realistically cannot have the exact same TID/SID/OT between games.
The games assign current handler based on the above values; there is no check for Version being different.
PKHeX uses the 3DS word filter for all formats, even for prior games. I'm not bypassing it for the Switch just because GameFreak didn't use one on the console.
1. Dump AHTB from ROM via pkNX
2. Rename the the smaller text file to SCBlocks.txt
3. Put SCBlocks.txt next to PKHeX.exe
4. Block Info will show the internal block names
5. Find block for the specific legend
6. Change the value
The save file is encrypted and signed; PKHeX unpacks it and checks its integrity.
This portion of PKHeX's code will reject an invalid save file to try and prevent a corrupted save from causing errors in the program.
https://github.com/kwsch/PKHeX/blob/3b5bcc9dad36d60aa8d5f2cd084a622621f37e92/PKHeX.WinForms/MainWindow/Main.cs#L725-L731
I just set a breakpoint before the if statement, and changed the version when the breakpoint was hit.
Somehow you changed your "Game" value to "Sun" (SN), which PK HeX does not like -- it expects SW/SH.
I skipped over that restriction and manually changed it to Sword, and exported the file. It's attached.
main_verchange