AssetStudio - Tool for read a list of asset in Unity
UABEA - Tool for pack a mod file back into the game
Extracting language files from the game
Following this Yu-Gi-Oh modding guide to use AssetStudio. However, the file we want to load is Yu-Gi-Oh! Master Duel\masterduel_Data\data.unity3d
Extract CARD_Desc, CARD_Indx and CARD_Name from the game using AssetStudio
In the directory with 3 files above. Run python "_CARD_decrypt_Desc+Indx+Name.py" to decrypt the file
Run python "_CARD_Name+Desc_split.py" to convert those files into JSON
Build and replacing to the game file
Once you update the CARD_Desc.dec.json and CARD_Desc.dec.json. Then run the command python "_CARD_merge+calc_index.py". This will give you 3 files CARD_Desc, CARD_Indx and CARD_Name
Rename 3 files above to be .txt. We doing this because UABEA only allow us to import .txt file.
We need to identify path_id of the file. Run AssetStudio and open the data.unity3d file from Yu-Gi-Oh! Master Duel\masterduel_Data
Remember the PathId of the language that you want to replace. Do this for every files (CARD_Desc, CARD_Indx and CARD_Name). Then close the AssetStudio.
Open UABEA. Open data.unity3d and then click Info.
Try to locate the all 3 CARD_ files with the same PathId. Click Plugins > Import .txt. And then importing .txt files from step 2.
In the Assets Info window. File > Save and then File > Close.
Then Save again on UABEA window. UABEA won't allow us to override opened file. So we need to save it as another name.
Replace the old data.unity3d file with the new one. (Make sure you made a copy of it)
Contribution
You can create a pull request to update CARD_Desc.dec.json and CARD_Desc.dec.json.