Hi Christina! Thanks for posting this idea!

While we are exploring interest from the community you can use this script, but please note that it is not a productized solution and past only basic testing flow.
You may need to adjust it slightly for your needs. For example, User team is not an OOTB field, so it's not included in the script

Here's an example of the list first:
Display Name; Username; Password; User Group; User Roles; Language; Email; User Type; External ID
User1 DN; User1; ; First Department; Reviewer; en; user1@your.company; Internal;
User2 DN; User2; ; Second Department, Third Department; Reviewer, Author; fr; user2@your.company; Internal; User2

Note that I used semicolon as a separator because I used commas when there is more than one Group or Role for a user.

$WsBaseUrl = "https://your.server/ISHWS"
$ishSession = New-IshSession -WsBaseUrl $WsBaseUrl -ishUserName "name_of_administrator_user" -ishPassword "administrator_password"

$userGroupObjects =  Find-IshUserGroup -RequestedMetadata (Set-IshRequestedMetadataField -IshSession $ishSession -Name "FISHUSERGROUPNAME" | Set-IshRequestedMetadataField -IshSession $ishSession -Name "FISHUSERGROUPNAME")
$userRoleObjects = Find-IshUserRole -IshSession $ishSession -RequestedMetadata (Set-IshRequestedMetadataField -IshSession $ishSession -Name "FISHUSERROLENAME")
$languageObjects = Get-IshLovValue -IshSession $ishSession -LovId DLANGUAGE

Function Get-UserGroups([string]$listOfUserGroups)
{
    $userGroups = $listOfUserGroups -split ',' | ForEach-Object { $_.Trim() }

    $userGroupsIshRefs = foreach ($userGroup in $userGroups) {
        $match = $userGroupObjects | Where-Object { $_.fishusergroupname -eq $userGroup }
        if ($match) { $match.IshRef }
    }

    return ($userGroupsIshRefs -join ', ')
}

Function Get-UserRoles([string]$listOfUserRoles)
{
    $userRoles = $listOfUserRoles -split ',' | ForEach-Object { $_.Trim() }

    $userRolesIshRefs = foreach ($userRole in $userRoles) {
        $match = $userRoleObjects | Where-Object { $_.fishuserrolename -eq $userRole }
        if ($match) { $match.IshRef }
    }

    return ($userRolesIshRefs -join ', ')
}

Function CreateUser(
    [string]$displayName,
    [string]$name,
    [string]$password,
    [string]$group,
    [string]$roles,
    [string]$language,
    [string]$email,
    [string]$type,
    [string]$externalId)
{
    $groupIshRefs = Get-UserGroups -listOfGroups.$user."User Group"
    $rolesIshRefs = Get-UserRoles -listOfRoles.$user."User Roles"
    $languageObject = $languages | Where-Object { $_.Label -eq $language }
    $userWorkingLanguage = $languageObject.IshRef

	$metadata = Set-IshMetadataField -IshSession $ishSession -Name FISHUSERDISPLAYNAME -Level None -Value $displayName `
                 | Set-IshMetadataField -IshSession $ishSession -Name PASSWORD -Level None -Value $password `
                 | Set-IshMetadataField -IshSession $ishSession -Name FUSERGROUP -Level None -ValueType Element -Value $groupIshRefs `
                 | Set-IshMetadataField -IshSession $ishSession -Name FISHUSERROLES -Level None -ValueType Element -Value $rolesIshRefs `
                 | Set-IshMetadataField -IshSession $ishSession -Name FISHUSERLANGUAGE -Level None -ValueType Element -Value $userWorkingLanguage `
                 | Set-IshMetadataField -IshSession $ishSession -Name FISHEMAIL -Level None -Value $email `
                 | Set-IshMetadataField -IshSession $ishSession -Name FISHUSERTYPE -Level None -Value $type `
                 | Set-IshMetadataField -IshSession $ishSession -Name FISHEXTERNALID -Level None -Value $externalId

	$user = Add-IshUser -IshSession $ishSession -Name $name -Metadata $metadata
}

$users = Get-Content "c:\file_path\users.csv" | ConvertFrom-Csv -Delimiter ";"
foreach ($user in $users) { 
    CreateUser `
         -displayName $user."Display Name" `
         -name $user.Username `
         -password $user.Password `
         -userGroup $user."User Group" `
         -userRole $user."User Roles" `
         -language $user.Language `
         -email $user.Email `
         -type $user."User Type" `
         -externalId $user."External ID"
}