This was my previous script:

@echo off
setlocal enabledelayedexpansion

REM ===========================
REM Configuration
REM ===========================

REM Path to the mkvmerge executable
set "MKVMERGE=C:\Program Files\MKVToolNix\mkvmerge.exe"

REM Destination directory for the processed files
set "DEST_DIR=D:\Video\MKVConvert"

REM ===========================
REM Setup
REM ===========================

REM Create destination directory if it does not already exist
if not exist "%DEST_DIR%" (
    mkdir "%DEST_DIR%"
)

REM ===========================
REM Processing
REM ===========================

REM Loop through each MKV file in the current directory
for %%a in (*.mkv) do (

    REM Check if the output file already exists
    if exist "!OUTPUT_FILE!" (
        echo Warning: Output file "!OUTPUT_FILE!" already exists. Skipping...
    ) else (
        REM Display a message indicating processing
        echo Processing: %%~nxa

        REM Execute mkvmerge to process the file
        "%MKVMERGE%" ^
            --ui-language en ^
            --priority highest ^
            --video-tracks 0 ^
            --audio-tracks 1 ^
            --subtitle-tracks 2 ^
            --no-attachments ^
            --no-global-tags ^
            --no-track-tags ^
            --no-chapters ^
            --language 0:en ^
            --track-name 0: ^
            --default-track-flag 0:yes ^
            --language 1:en ^
            --track-name 1: ^
            --default-track-flag 1:yes ^
            --sub-charset 2:UTF-8 ^
            --language 2:en ^
            --track-name 2: ^
            --default-track-flag 2:yes ^
            --title "" ^
            --track-order 0:0,0:1,0:2 ^
            --output "!OUTPUT_FILE!" ^
            "%%~fa"

        REM Check if the processing was successful
        if errorlevel 1 (
            echo Error: Failed to process "%%~nxa". Please check the input file and try again.
            echo.
        ) else (
            echo Successfully processed "%%~nxa"
            echo.
            REM Increment the processed files counter
            set /a processed_count+=1
        )
    )
)

REM ===========================
REM Completion Message
REM ===========================

REM Display a completion message for processing
echo.
echo All MKV files have been processed and saved in %DEST_DIR%.

REM Pause the script to allow the user to see the output
pause

This is my current, updated script:

@echo off

REM ===========================
REM Configuration
REM ===========================

REM Path to the mkvmerge executable
set "MKVMERGE=C:\Program Files\MKVToolNix\mkvmerge.exe"

REM Destination directory for the processed files
set "DEST_DIR=D:\Video\MKVConvert"

REM ===========================
REM Setup
REM ===========================

REM Create destination directory if it does not already exist
if not exist "%DEST_DIR%" (
    echo Creating destination directory: "%DEST_DIR%"
    mkdir "%DEST_DIR%"
    if errorlevel 1 (
        echo Error: Failed to create destination directory.
        echo Please check permissions or the path and try again.
        echo.
        pause
        exit /b 1
    )
)

REM Check if mkvmerge exists
if not exist "%MKVMERGE%" (
    echo Error: mkvmerge executable not found at "%MKVMERGE%".
    echo Please verify the path to mkvmerge.exe.
    echo.
    pause
    exit /b 1
)

REM ===========================
REM Processing
REM ===========================

REM Initialize the counter for processed files
set /a processed_count=0

REM Loop through each MKV file in the current directory
for %%a in (*.mkv) do (

    REM Check if the output file already exists
    if exist "%DEST_DIR%\%%~nxa" (
        echo Warning: Output file "%DEST_DIR%\%%~nxa" already exists. Skipping...
        echo.
    ) else (
        REM Display a message indicating processing
        echo Processing: "%%~nxa"

        REM Execute mkvmerge to process the file
        "%MKVMERGE%" ^
            --ui-language en ^
            --priority highest ^
            --video-tracks 0 ^
            --audio-tracks 1 ^
            --subtitle-tracks 2 ^
            --no-attachments ^
            --no-global-tags ^
            --no-track-tags ^
            --no-chapters ^
            --language 0:en ^
            --track-name 0: ^
            --default-track-flag 0:yes ^
            --language 1:en ^
            --track-name 1: ^
            --default-track-flag 1:yes ^
            --sub-charset 2:UTF-8 ^
            --language 2:en ^
            --track-name 2: ^
            --default-track-flag 2:yes ^
            --title "" ^
            --track-order 0:0,0:1,0:2 ^
            --output "%DEST_DIR%\%%~nxa" ^
            "%%~fa"

        REM Check if the processing was successful
        if errorlevel 1 (
            echo Error: Failed to process "%%~nxa". Please check the input file and try again.
            echo.
        ) else (
            echo Successfully processed "%%~nxa"
            echo.
            REM Increment the processed files counter
            set /a processed_count+=1
        )
    )
)

REM ===========================
REM Completion Message
REM ===========================

REM Check the number of processed files and display an appropriate message for processing
if %processed_count% EQU 0 (
    echo No MKV files were processed. All existing files were skipped or no MKV files were found in current directory.
) else (
    if %processed_count% EQU 1 (
        echo 1 MKV file has been processed and saved in "%DEST_DIR%".
    ) else (
        echo %processed_count% MKV files have been processed and saved in "%DEST_DIR%".
    )
)

REM Pause the script to allow the user to see the output
pause


Please look through and understand the changes that I've made and think about why I've done it that way. When you're ready I will send you a different script and you will incorporate those changes into the new script. Does that sound good or do you have any questions?