Idk if this gonna help, but this is regarding the item.msgbnd.dcx fmg files

So, for example, you have the detailed item description mod and another mod (e.g. a new weapon mod) that add something to the game, you merged the two regulation.bin files, put it in mod folder, then open the game, then find out that the name or the description of the item is missing. Well, here's how I kinda fixed it.

Use WitchyBND on item.msgbnd.dcx on both mods, you will get the folder that has the fmg files, depending on what the mod that you have installed, you will only change the files that relates to it (So for a weapon mod, you will only change the files that starts with weapon), use WitchyBND again on the same fmg file of both mods , you will get a xml file, this where you gonna use a program like FlashDevelop, open the xml file (detailed item description) with FlashDevelop, and the other mod (weapon mod) on notepad or edge, you want to look in the other mod the text id (For the weaponname.fmg file, look for its name) , and see what's added or changed, then go to FlashDevelop and change the text id to the other mod's text id, then go save the file, go back to the fmg folder, delete the fmg file that has the same name of the xml file, Use WitchyBND on the xml file, then do the same thing for the other fmg files. Then, you should be able to see the name/description of the item in game.

I know this is long and messy, but it might help someone who is in the same position that I was.