PHP 是最好的语言, 但是……

<?php
if ($argc < 2) {
    die();
}
if (!is_file($argv[1])) {
    die();
}
$offset = $argv[2] ?? 0;
 
// Search and Replace using Regular Expression with Arithmetic Evaluation
echo preg_replace_callback(
        '~\<z\>(.*)\</z\>~i', // pattern for Z coordinate
        function ($matches) {
            global $offset;
            return "<z>".($matches[1] + $offset)."</z>";
        },
        file_get_contents($argv[1])
);

Option Explicit 

Dim args
Set args = Wscript.Arguments

If args.Count < 2 Then
    WScript.Echo "First Parameter: BSM Path. Second Parameter: Z Offset."
    WScript.Quit
End If 

Dim fs
Set fs = CreateObject("Scripting.FileSystemObject") 

Dim bsm: bsm = args(0)
Dim offset: offset = args(1)

If Not IsNumeric(offset) Then
    WScript.Echo "Second Parameter: Not a Number"
    WScript.Quit
End If 

offset = CDbl(offset)

If Not fs.FileExists(bsm) Then
    WScript.Echo "File Not Found: " & bsm
    WScript.Quit    
End If

Dim text
Set text = fs.OpenTextFile(bsm, 1)

Dim objRegEx
Set objRegEx = CreateObject("VBScript.RegExp")

objRegEx.Global = True
objRegEx.IgnoreCase = True
objRegEx.Pattern = "<Z\>(.*)\</Z\>"

Dim s, matches
Do Until text.AtEndOfStream
    s = text.ReadLine
    Set matches = objRegEx.Execute(s)
    If matches.Count > 0 Then
        WScript.Echo "<Z>" & matches.Item(0).SubMatches.Item(0) + offset & "</Z>"
    Else
        WScript.Echo s
    End If
Loop

text.Close
Set text = Nothing
Set fs = Nothing
Set args = Nothing
Set objRegEx = Nothing