Hello,
i have been working for some time on a GUI based o365 LAP installer for our users, that have no install rights. Since our OS Task seqeunce installs only English.
The installer it is written in powershell with Windows Forms.
It can be used as online installer, or if you want, download the install files with setup.exe /download  configure.xml and pack the office folder with the scritp and setup.exe
Te setup.exe commes from Microsoft's Office Deployment Tool - download , run and point to direcory. - You only need the setup file from ODT.
The script is generating the required xml and owerwites it as well for reuse.


It is deployed from SCCM for system, but st so that users can interact with it. Same scrit is used for Install, Uninstal and Repair.
The detection is handeld by checking the same registry entries as used in the script with OR parameter, so any one of them can satisfy the detection.
Feel free to change as you like :)

Here is the ps script:

# Hide PowerShell Console window.
Add-Type -Name Window -Namespace Console -MemberDefinition '
[DllImport("Kernel32.dll")]
public static extern IntPtr GetConsoleWindow();
[DllImport("user32.dll")]
public static extern bool ShowWindow(IntPtr hWnd, Int32 nCmdShow);
'
$consolePtr = [Console.Window]::GetConsoleWindow()
[Console.Window]::ShowWindow($consolePtr, 0)

# Create main form.
Add-Type -AssemblyName System.Windows.Forms
[System.Windows.Forms.Application]::EnableVisualStyles()

$Form = New-Object system.Windows.Forms.Form
$Form.ClientSize = '600,400'
$Form.text = "Office 365 Language Pack Installer"
$Form.TopLevel = $true
$form.startposition = 'centerscreen'
$form.FormBorderStyle = 'Fixed3D'
$form.Icon = [System.Drawing.SystemIcons]::WinLogo

# Add combobox. Use array for datasource.
$SelectLanguage = New-Object system.Windows.Forms.ComboBox
$SelectLanguage.DropDownStyle = [System.Windows.Forms.ComboBoxStyle]::DropDownList
$SelectLanguage.text = "Select Language"
$SelectLanguage.width = 280
$SelectLanguage.height = 20
$items=[collections.arraylist]@(
    [pscustomobject]@{Name='Chinese Language Pack';Value='zh-cn'}
    [pscustomobject]@{Name='Czech Language Pack';Value='cs-cz'}
    [pscustomobject]@{Name='Danish Language Pack';Value='da-dk'}
    [pscustomobject]@{Name='Estonian Language Pack';Value='et-ee'}
    [pscustomobject]@{Name='Finish Language Pack';Value='fi-fi'}
    [pscustomobject]@{Name='French Language Pack';Value='fr-fr'}
    [pscustomobject]@{Name='German Language Pack';Value='de-de'}
    [pscustomobject]@{Name='Greek Language Pack';Value='el-gr'}
    [pscustomobject]@{Name='Hungarian Language Pack';Value='hu-hu'}
[pscustomobject]@{Name='Italian Language Pack';Value='it-it'}
[pscustomobject]@{Name='Korean Language Pack';Value='ko-kr'}
    [pscustomobject]@{Name='Latvian Language Pack';Value='lv-lv'}
    [pscustomobject]@{Name='Lithuanian Language Pack';Value='lt-lt'}
    [pscustomobject]@{Name='Nederlands Language Pack';Value='nl-nl'}
    [pscustomobject]@{Name='Norwegian Language Pack';Value='nb-no'}
    [pscustomobject]@{Name='Polish Language Pack';Value='pl-pl'}
    [pscustomobject]@{Name='Russian Language Pack';Value='ru-ru'}
    [pscustomobject]@{Name='Slovak Language Pack';Value='sk-sk'}
    [pscustomobject]@{Name='Spanish Language Pack';Value='es-es'}
    [pscustomobject]@{Name='Swedish Language Pack';Value='sv-se'}
    [pscustomobject]@{Name='Turkish Language Pack';Value='tr-tr'}
)
$SelectLanguage.DataSource=$items
$SelectLanguage.DisplayMember='Name'
$SelectLanguage.location = New-Object System.Drawing.Point(150,40)
$SelectLanguage.Font = 'Microsoft Sans Serif,10'

# Add buton with click event. Based on registry presence, set $addrem variable. Export xml and owerwrite if it already exists.
# Start-Process with -Wait so that the forms window will not be selectable while installtion is running.
# use $this.Text to update the button once installtion finishes.
$close = New-Object system.Windows.Forms.Button
$close.text = "Install / Uninstall"
$close.width = 120
$close.height = 30
$close.location = New-Object System.Drawing.Point(230,80)
$close.Font = 'Microsoft Sans Serif,10'
$close.Add_Click({
$option = $SelectLanguage.SelectedItem.value
$optionpath = 'O365ProPlusRetail - '+$option
$regpath = "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall"
if(Test-Path $(join-path $regpath $optionpath)) {
$addrem = 'Remove'
} else {
$addrem = 'Add'
}

$xmltemplate = @"
<Configuration>
<$addrem OfficeClientEdition="64">
<Product ID="LanguagePack">
<Language ID="$option" />
</Product>
</$addrem>
     <Display Level="Full" AcceptEULA="True" />
</Configuration>
"@
$xmltemplate | Out-File -FilePath $("" + $pwd + "\" + "configure.xml")
Start-Process -Wait -NoNewWindow "$pwd\setup.exe" -ArgumentList "/configure $pwd\configure.xml"
$this.Text = if(Test-Path $(join-path $regpath $optionpath)) {'Remove'} else {'Add'}
}
)

# Update button text when a value in combobox is selected, based on installation status.
$SelectLanguage_SelectedIndexChanged=
{$option = $SelectLanguage.SelectedItem.value
$optionpath = 'O365ProPlusRetail - '+$option
$regpath = "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall"
if(Test-Path $(join-path $regpath $optionpath)) {$close.text = 'Remove'} else {$close.text = 'Add'}
}
$SelectLanguage.add_SelectedIndexChanged($SelectLanguage_SelectedIndexChanged)

# Add informational text for the user & hope they read it :)
$TextBox1 = New-Object system.Windows.Forms.TextBox
$TextBox1.multiline = $true
$TextBox1.text ="Please close all running Office applications including Skype for Business!`
When the installer closes running applications, it will not save your work, so do it manually.`
This is an ONLINE installation, about 500MB will be downloaded from internet.`
If you require to install more than one language, please do it one by one.`
Editing and Display language defaults can be set at:`
Start -> Microsoft Office Tools -> Office Language preferences."
$TextBox1.width = 570
$TextBox1.height = 200
$TextBox1.location = New-Object System.Drawing.Point(15,150)
$TextBox1.Font = 'Arial,11'
$textBox1.TextAlign = 'Center'

$Label1 = New-Object system.Windows.Forms.Label
$Label1.text = "Select language pack to Install."
$Label1.AutoSize = $true
$Label1.width = 25
$Label1.height = 10
$Label1.location = New-Object System.Drawing.Point(195,12)
$Label1.Font = 'Microsoft Sans Serif,10'

$Form.controls.AddRange(@($SelectLanguage,$close,$TextBox1,$Label1))

# This is the same button update text user when selecting a value in combobox. But this one runs when the form loads so that the fisrst entry in the list is resolved.
$Form.Add_Load({
$option = $SelectLanguage.SelectedItem.value
$optionpath = 'O365ProPlusRetail - '+$option
$regpath = "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall"
if(Test-Path $(join-path $regpath $optionpath)) {$close.text = 'Remove'} else {$close.text = 'Add'}
})
[void]$form.ShowDialog()