conversion from .kml to .pln or .flt files

[routeconverter]

Maybe this makes it clear... I've removed everything from your .pln file that is not available from the .kml file.
This is the result:

<?xml version="1.0" encoding="UTF-8"?>

<SimBase.Document Type="AceXML" version="1,0">
    <FlightPlan.FlightPlan>
        <Title>EDDM to LKPR</Title>
        <ATCWaypoint id="EDDM">
            <WorldPosition>N48° 21' 13.62",E11° 47' 9.91",+001487.00</WorldPosition>
        </ATCWaypoint>
        <ATCWaypoint id="LKPR">
            <WorldPosition>N50° 6' 3.00",E14° 15' 36.00",+001234.00</WorldPosition>
        </ATCWaypoint>
    </FlightPlan.FlightPlan>
</SimBase.Document>

Please put this into a test.pln file and try to import it to MSFT2020. If it fails, interpret the error message and add information from the original file until it's correctly imported.