MSFS does not launch any of the apps in exe.xml. The path of both apps is correct.

Below the contents of exe.xml

<?xml version="1.0" encoding="utf-8" ?>
<SimBase.Document Type="SimConnect" version="1,0">
    <Descr>SimConnect</Descr>
    <Filename>SimConnect.xml</Filename>
    <Disabled>False</Disabled>
    <Launch.Addon>
        <Name>IVAO Pilot Client</Name>
        <Disabled>False</Disabled>
        <ManualLoad>False</ManualLoad>
        <Path>E:\MSFS2020\IVAO\PilotCore\pilot_core_fs2020.exe</Path>
        <NewConsole>False</NewConsole>
    </Launch.Addon>
    <Launch.Addon>
        <Name>FSRealistic</Name>
        <Disabled>false</Disabled>
        <Path>E:\FSRealistic\FSRealistic.exe</Path>
    </Launch.Addon>
</SimBase.Document>

 

Your file has been derived from the simconnect.xml, hasn't it? That is not really the correct format. The sim may not mind so much, but still, the exe.xml looks like this:

<?xml version="1.0" encoding="utf-8"?>
<SimBase.Document Type="Launch" version="1,0">
  <Descr>Launch</Descr>
  <Filename>exe.xml</Filename>
  <Disabled>False</Disabled>
  <Launch.ManualLoad>False</Launch.ManualLoad>
  <Launch.Addon>
      <Name>IVAO Pilot Client</Name>
      <Disabled>False</Disabled>
      <ManualLoad>False</ManualLoad>
      <Path>E:\MSFS2020\IVAO\PilotCore\pilot_core_fs2020.exe</Path>
      <NewConsole>False</NewConsole>
  </Launch.Addon>
  <Launch.Addon>
      <Name>FSRealistic</Name>
      <Disabled>False</Disabled>
      <Path>E:\FSRealistic\FSRealistic.exe</Path>
  </Launch.Addon>
</SimBase.Document>

Be mindful that it is MSFS that is starting your apps. So if these apps have been set up as to start "As Administrator", then you must start MSFS "As Administrator" too. Otherwiese the sim doesn't have enough privileges to run your apps.

Oh, and make sure that the encoding in the ?xml Tag matches the actual encoding of your file. Using Notepad++ this is done in the menu "Encoding" - select "UTF-8 BOM" for this file, then save it. 
Or change the "encoding" attribute to the correct value. With a standard Windows textfile it is often encoding="Windows-1252".

Edited August 5, 20223 yr by Lorby_SI

The problem was the admin rights -  apps starting as admin, while msfs not. I also changed the exe.xml format as you suggested - looks more appropriate

Thanks for your help !