Select current folder or any relative folder within Command Prompt

I found this thread, found that there's an undocumented feature /fp:"folder path". One user said Microsoft already provides APIs to normalize paths.

Visual Studio Code, Notepad++, Sublime Text can all parse folder paths correctly without any issue.

rem Start VSCode in current folder
code .

rem Open Example.txt in Notepad++
npp .\Example.txt

Can Mp3Tag do the same with or without /fp?

I want to open a relative file or a folder within CMD.exe without any .BAT file like so:

cd /D "D:\My Music\"

rem Select one song
"C:\...\mp3tag.exe" ".\Songs from Youtube\Hello World.mp3"

rem Select a relative folder
"C:\...\mp3tag.exe" ".\Songs from Youtube"

It should look for files in Current Working Directory (Wikipedia).
It should not look in Program Files because NO music file in Program Files.

This is not quite true.
The command line switch is actually "/fp:"<full-qualified path to directory>"
There is a section in the help dedicated to the command line parameters.
So in respect to specification, your observation is correct: a relative path does not work as a full-qualified path is required - and in that respect MP3tag behaves like specified.