Add my own dictionary file or a word to a specific dictionary?

This post is more about managing multilingual spell checking in general.
my platform: win10
I am trying to keep separate dictionary files for different languages so I can use them across different apps. Is there a way to specify which dictionary file I want to add a new word in?

Things I have tried

I’ve found that dictionaries of languages chosen from the dropdown menu are stored in the following path:
C:\Users<user>\AppData\Roaming\obsidian\Dictionaries
I tried to manually append a list of words in these files, however, they are in .bdic format and when I tried to open them in chrome, chrome won’t display the content, instead I was prompted a “save as” window to save the exactly file again lol. not sure what’s happening here.

I also tried adding a language1.txt file with some made up words in it, apparently they are not automatically marked as correct when I type them again in the obsidian editor.

Then I checked the app.json file in .obsidian folder, found the values of key spellcheckLanguages are not exactly the file names in the dictionary folder, and also not the same as listed in the UI drop down menu. Not sure how they are parse but I appended language1 to the list in app.json anyways, the UI then showed language1 (Not Available) in addition to the list of languages I already chosen from the menu. Again the made-up words in the file are not recognized automatically.

What I’m trying to do

Preferably, I am hoping to be able to add my own dictionary files for languages not included in the dropdown menu, and when I click an incorrect word, the pop-up menu can show options like “add to dictionary_file 1”, “add to dictionary_file 2” etc…

If this is not realistic, I wonder if there’s a way to add shortcuts to quick add a word to dictionary, like when the cursor is at a word marked incorrect, I can add it by pressing a key sequence instead of having to right click and locate the “add to dictionary” option. The right-click menu loads much slower when I right click an incorrect word, which is quite annoying.

Thanks!