You could try this:
$paths = "\\server1\unc\path", "\\server1\unc\path"
Get-ChildItem -Path $paths
| Where-Object {$_.lastwritetime -gt (Get-Date).addDays(-1)}
| Select-Object @{n="Server";e={([uri]$_.FullName).Host}},
@{n="Filename";e={$_.Name}},
@{n="Date";e={$_.CreationTime}},
@{n="FileSize(MB)";e={[Math]::Round($_.Length/1MB,3)}}
| Export-Csv test.csv -NoTypeInformation
It extracts the servername from the UNC path and renames the other properties with the names you specified.