Kingdoms.exe, export_descr_character_traits.txt and --io.file_first

I'm experiencing some slight issues with editing the export_descr_character_traits.txt file to reflect my earlier RTW/MTW2 settings with the Kingdoms expansion. Of course I'm using the original, unpacked export_descr_character_traits.txt file from the british_isles mod and not something else. I simply changed my stats in the new traits.txt file to correlate with my previous edits.

Issue: I'm playing the british_isles campaign otherwise unedited, but wish to import the changes I usually input to the export_descr_character_traits.txt file. Having unpacked the file and copied it to the \data folder of the mod, I launched the game using a shortcut like so:

"C:\install_folder\Medieval II Total War\kingdoms.exe" --features.mod=mods/british_isles --io.file_first

.. but unfortunately my changes did not manifest though otherwise Kingdoms works perfectly.

Other tests:

- Installing a mod that adds a faction and graphics to british_isles\data actually works (if I copy my export_descr_character_traits.txt on top of it nothing happens though, the new faction and graphics work but not the character traits edit)

- Updating a file that changes a city name inside the \text\imperial_campaign_regions_and_settlement_names.txt.strings.bi produces a crash, so apparently my IO file_fist switch works... though it shouldn't crash but that's not the point, I want to change other things i.e. how the characters acquire traits.

Is the kingdoms.exe incompatible with the file and I should stop trying, or am I doing something stupidly wrong? It's been a few years since I last modded MTW2 so I wouldn't be surprised if I just don't see something obvious.

Ok everything else works, that's settled. I can mod just about any other aspect of the game but the character_traits with the same setup.

I've edited the goodtrader / badtrader traits to only give 50% of the effects both negative and good and played for a while, but they do not apply unlike in RTW or MTW2 pre patch 1.2.

I'm really wondering what's the reason.