Python Code with Plugin "Create Points Layer from Spreadsheet" - python-3.x

Question

I'm new to python, that is the first problem.
Secondly I am trying to automate the task of adding vector point layers from spreadsheets (xlsx-files) with Python.
The task can be done manually with the plugin "add spreadsheet layer".
I have a folder with roughly 20 xlsx-files that need to be added into the QGIS-project as vector point layers.
I have tried the following code snippet, to check if the core task of adding a spreadsheet layer actually works:
The Computer has a Win7 OS. The program in question is Python which is contained in the program QGIS 3.4.
The Plugin that I want to control through python is called "add spreadsheet layer".
from qgis.core import *
import processing
processing.run("qgis:createpointslayerfromtable",
{'INPUT':r'C:\Users\Desktop\PlayItAll\Test.xlsx',
'XFIELD':'X_Pos',
'YFIELD':'Y_Pos',
'ZFIELD':None,
'MFIELD':None,
'TARGET_CRS':QgsCoordinateReferenceSystem('EPSG:4326'),
'OUTPUT':r'memory'})
It produces this error:
File "C:/PROGRA1/QGIS31.4/apps/qgis/./python/plugins\processing\core\Processing.py", line 183, in runAlgorithm
raise QgsProcessingException(msg)
I have contacted the programmer of the plugin and he gave me this code to try:
import processing
processing.runAndLoadResults("qgis:createpointslayerfromtable",
{
'INPUT':r'C:\Users\username\Desktop\Delete\test.xlsx',
'XFIELD':'Longitude',
'YFIELD':'Latitude',
'ZFIELD':None,
'MFIELD':None,
'TARGET_CRS':QgsCoordinateReferenceSystem('EPSG:4326'),
'OUTPUT':'memory'
})
For him it worked, for me it didn't.
I got this on the processing tab:
2019-07-03T13:19:43 CRITICAL Traceback (most recent call last):
File "C:/PROGRA~1/QGIS3~1.4/apps/qgis/./python/plugins\processing\algs\qgis\PointsLayerFromTable.py", line 112, in processAlgorithm
fields, wkb_type, target_crs)
Exception: unknown
2019-07-03T13:19:43 CRITICAL Traceback (most recent call last):
File "C:/PROGRA~1/QGIS3~1.4/apps/qgis/./python/plugins\processing\algs\qgis\PointsLayerFromTable.py", line 112, in processAlgorithm
fields, wkb_type, target_crs)
Exception: unknown
2019-07-03T13:19:43 CRITICAL There were errors executing the algorithm.
The "python warnings" tab showed this:
2019-07-03T13:19:43 WARNING warning:__console__:1: ResourceWarning:
unclosed file
traceback: File "C:/PROGRA~1/QGIS3~1.4/apps/qgis/./python\console\console.py", line 575, in runScriptEditor
self.tabEditorWidget.currentWidget().newEditor.runScriptCode()
File "C:/PROGRA~1/QGIS3~1.4/apps/qgis/./python\console\console_editor.py", line 629, in runScriptCode
.format(filename.replace("\\", "/"), sys.getfilesystemencoding()))
File "C:/PROGRA~1/QGIS3~1.4/apps/qgis/./python\console\console_sci.py", line 635, in runCommand
more = self.runsource(src)
File "C:/PROGRA~1/QGIS3~1.4/apps/qgis/./python\console\console_sci.py", line 665, in runsource
return super(ShellScintilla, self).runsource(source, filename, symbol)
File "C:\PROGRA~1\QGIS3~1.4\apps\Python37\lib\code.py", line 74, in runsource
self.runcode(code)
File "C:\PROGRA~1\QGIS3~1.4\apps\Python37\lib\code.py", line 90, in runcode
exec(code, self.locals)
File "", line 1, in