Get Worksheet Data Array (Standard Methods)
UnhideWsCellsAndRemoveFilters()

Well thats a real strange name. Wouldn't it be better to replace Unhide with Show? Like ShowWsCellsAndRemoveFilters() ?  

CellContainingStringInRange()

You should declare your variables as near as possible to their usage. This together with reverting the if condition to return early would lead to  

Public Function CellContainingStringInRange(ByRef rngSearch As Range, ByVal strSearch As String) As Range

    Set CellContainingStringInRange = rngSearch.Find(strSearch, LookIn:=xlValues)
    If CellContainingStringInRange IsNot Nothing Then
        Exit Function
    End If

    Dim errorMessage As String
    errorMessage = "Couldn't find cell """ &amp; strSearch &amp; """ in " &amp; rngSearch.Worksheet.name
    PrintErrorMessage errorMessage, stopExecution:=True
End Function


GetWsDataRange()

At first glance at this  


Dim wbSource As Workbook, wsSource As Worksheet
Set wbSource = ActiveWorkbook
Set wsSource = ActiveSheet  



it will be overseen that wbSource and wsSource are different objects. You should consider to use some vertical spacing to separate these and/or to use different names like sourceBook and sourceSheet. The same is true for the method arguments wbTarget and wsTarget.  

Generally declaring multiple variables on the same line should be avoided because it is much harder to read/maintain.  

Having the dataRange As Range doesn't provide any value because it is only used "once". You can assign the return value directly.  

Implementing this points and having the declarations as near to their usage as possible and on separate lines will lead to  

Public Function GetWsDataRange(ByRef targetBook As Workbook, ByRef targetSheet As Worksheet, ByVal topLeftCellText As String, ByVal useCurrentRegion As Boolean _
                            , ByVal searchStartRow As Long, ByVal searchStartColumn As Long _
                            , ByVal searchEndRow As Long, ByVal searchEndColumn As Long) As Range

    Dim sourceBook As Workbook
    Set sourceBook = ActiveWorkbook

    Dim sourceSheet As Worksheet
    Set sourceSheet = ActiveSheet

    targetBook.Activate
    targetSheet.Activate
    ShowWsCellsAndRemoveFilters ws

    Dim searchRange As Range
    Set searchRange = targetSheet.Range(Cells(searchStartRow, searchStartColumn), Cells(searchEndRow, searchEndColumn))

    Dim topLeftCell As Range
    Set topLeftCell = CellContainingStringInRange(searchRange, topLeftCellText)

    Dim dataRange As Range

    If useCurrentRegion Then
        Set GetWsDataRange = topLeftCell.CurrentRegion
    Else
        Dim lastRow As Long
        lastRow = Cells(Rows.Count, topLeftCell.Column).End(xlUp).row

        Dim lastCol As Long
        lastCol = Cells(topLeftCell.row, Columns.Count).End(xlToLeft).Column

        Set GetWsDataRange = targetSheet.Range(topLeftCell, Cells(lastRow, lastCol))
    End If

    sourceBook.Activate
    sourceSheet.Activate

End Function