This gist includes a class and functions for checking whether a file (for example, a script or an ADMX template) has an additional file with localized data that matches the specified culture.

DotNetLocalizedStringFile.ps1

#Requires -Version 5.1

class   DotNetLocalizedStringFile   {
    [System.IO.FileInfo]
    $SourceFile
    [cultureinfo]
    $CultureInfo
    [System.IO.FileInfo]
    $LocalizedFile
    [bool]
    $Exists
    #   Method: returns the localized file
    [System.IO.FileInfo]
    _getLocalizedFile(
        [System.IO.FileInfo]$fileInfo,
        [cultureinfo]$culture,
        [string]$extension,
        [bool]$byLCID
    )   {
        if  ($byLCID)   {
            [string]$cultureFolder  =   $culture.LCID
        }
        else {
            [string]$cultureFolder  =   $culture.Name
        }
        [string]$outFilePath        =   [System.IO.Path]::ChangeExtension(
            [System.IO.Path]::Combine(
                $fileInfo.DirectoryName,$cultureFolder,$fileInfo.BaseName
            ),$extension
        )
        [System.IO.FileInfo]$outFileInfo    =   [System.IO.FileInfo]::new($outFilePath)
        return  $outFileInfo
    }
    #   Constructor:    default (no arguments)
    DotNetLocalizedStringFile(){}
    #   Constructor:    from System.IO.FileInfo, cultureinfo and extension
    DotNetLocalizedStringFile(
        [System.IO.FileInfo]$fileInfo,
        [cultureinfo]$culture,
        [string]$extension
    )   {
        $this.SourceFile    =   $fileInfo
        $this.CultureInfo   =   $culture
        $this.LocalizedFile =   $this._getLocalizedFile($fileInfo,$culture,$extension,$false)
        $this.Exists        =   $this.LocalizedFile.Exists
    }
    #   Constructor:    from System.IO.FileInfo, cultureinfo and extension
    DotNetLocalizedStringFile(
        [System.IO.FileInfo]$fileInfo,
        [cultureinfo]$culture,
        [string]$extension,
        [bool]$byLCID
    )   {
        $this.SourceFile    =   $fileInfo
        $this.CultureInfo   =   $culture
        $this.LocalizedFile =   $this._getLocalizedFile($fileInfo,$culture,$extension,$byLCID)
        $this.Exists        =   $this.LocalizedFile.Exists
    }
    #   Constructor:    from file path, culture name and extension
    DotNetLocalizedStringFile(
        [string]$filePath,
        [string]$cultureName,
        [string]$extension
    )   {
        $this.SourceFile    =   [System.IO.FileInfo]::new($filePath)
        $this.CultureInfo   =   [cultureinfo]::GetCultureInfo($cultureName)
        $this.LocalizedFile =   $this._getLocalizedFile($this.SourceFile,$this.CultureInfo,$extension,$false)
        $this.Exists        =   $this.LocalizedFile.Exists
    }
    #   Constructor:    from file path, culture name and extension
    DotNetLocalizedStringFile(
        [string]$filePath,
        [string]$cultureName,
        [string]$extension,
        [bool]$byLCID
    )   {
        $this.SourceFile    =   [System.IO.FileInfo]::new($filePath)
        $this.CultureInfo   =   [cultureinfo]::GetCultureInfo($cultureName)
        $this.LocalizedFile =   $this._getLocalizedFile($this.SourceFile,$this.CultureInfo,$extension,$byLCID)
        $this.Exists        =   $this.LocalizedFile.Exists
    }
}

enum FileOutputType {
    Missing =   0
    Present =   1
}

function Get-DotNetLocalizedStringFile {
    [CmdletBinding()]
    param   (
        [Parameter(Mandatory,ValueFromPipeline,ValueFromPipelineByPropertyName)]
        [Alias('FullName')]
        [System.IO.FileInfo]
        $Path,
        [Parameter()]
        [string]
        $Extension,
        [Parameter()]
        [string[]]
        $UICulture,
        [Parameter()]
        [FileOutputType]
        $OutputType,
        [Parameter()]
        [switch]
        $ByLCID
    )
    begin   {
        if  ($PSBoundParameters.ContainsKey('UICulture'))   {
            [cultureinfo[]]$cultureInfoAll  =   $UICulture.ForEach({[cultureinfo]::new($_)})
        }
        else {
            [cultureinfo[]]$cultureInfoAll  =   [cultureinfo]::CurrentUICulture
        }
    }
    process {
        foreach ($cultureInfo   in  $cultureInfoAll)    {
            [DotNetLocalizedStringFile]$outputObject    =   [DotNetLocalizedStringFile]::new($Path,$cultureInfo,$Extension,$ByLCID)
            if  (-not   $PSBoundParameters.ContainsKey('OutputType'))   {
                $outputObject
                continue
            }
            [bool]$shouldPresent    =   [int]$OutputType
            [bool]$shouldOutput     =   $outputObject.Exists    -eq $shouldPresent
            if  (-not   $shouldOutput)  {   continue    }
            $outputObject
        }
    }
    end     {}
}

function Get-PolicyLocalizationFile {
    [CmdletBinding()]
    param   (
        [Parameter(Mandatory)]
        [string]
        $Path,
        [Parameter()]
        [string[]]
        $UICulture,
        [Parameter()]
        [FileOutputType]
        $OutputType
    )
    begin   {
        if  (-not   $PSBoundParameters.ContainsKey('UICulture'))    {
            $UICulture  =   [System.Windows.Forms.InputLanguage]::InstalledInputLanguages.Culture.Name
        }
        $splatGetOutput =   @{
            UICulture   =   $UICulture
            Extension   =   '.adml'
        }
        if  ($PSBoundParameters.ContainsKey('OutputType'))  {
            $splatGetOutput.Add('OutputType',$OutputType)
        }
    }
    process {
        Get-ChildItem -Path $Path -Filter '*.admx' -File | Get-DotNetLocalizedStringFile @splatGetOutput
    }
    end     {}
}